Family Discussion Post

SUSAN M. MCHALE The Pennsylvania State University

KIMBERLY A. UPDEGRAFF Arizona State University*

SHAWN D. WHITEMAN Purdue University**

Sibling Relationships and Influences in Childhood

and Adolescence

The authors review the literature on sibling relationships in childhood and adolescence, starting by tracing themes from foundational research and theory and then focusing on empirical research during the past 2 decades. This literature documents siblings’ centrality in family life, sources of variation in sibling relationship qualities, and the significance of siblings for child and adolescent development and adjustment. Sibling influences emerge not only in the context of siblings’ frequent and often emotionally intense interactions but also by virtue of siblings’ role in larger family system dynamics. Although siblings are building blocks of family structure and key players in family dynamics, their role has been relatively neglected by family scholars and by those who study close relationships. Incorporating study of siblings into family research provides novel insights into the operation of families as social and socializing systems.

Department of Human Development and Family Studies, 601 Oswald, The Pennsylvania State University, University Park, PA 16801 (mchale@psu.edu).

*School of Social and Family Dynamics, 951 S. Cady Mall, Arizona State University, Tempe, AZ 85287.

**Department of Human Development and Family Studies, Hanley Hall, Purdue University, West Lafayette, IN 47907.

Key Words: adolescents, childhood/children, family process, sibling relations.

Siblings are a fixture in the family lives of children and adolescents, and a body of work documents their role in one another’s everyday experiences as companions, confidantes, com- batants, and as the focus of social comparisons. Research on sibling relationships has been aimed at identifying factors that explain these and other social dynamics between siblings and at exam- ining the role of sibling experiences in youth development and well-being. From this work we know that sibling relationships are shaped by factors ranging from child characteristics to cultural norms and values. We also know that siblings can have direct effects on one another’s development when they serve as social part- ners, role models, and foils and that siblings can influence one another indirectly by virtue of their impact on larger family dynamics—such as by serving as building blocks of the fam- ily structure, holding a favored family niche, or diluting family resources (McHale, Kim, & Whiteman, 2006).

Recent national data document the ubiquity of siblings in U.S. families, even in the face of declines in family size. Data from the Integrated Public Use Microdata Series’ harmonization of the 2010 Current Population Survey (King et al., 2010) indicate that 82.22% of youth age 18 and under lived with at least one sibling—a higher percentage than were living in a household with a father figure (78.19%). In 2010, the number of siblings in the household for youth age 18 and

Journal of Marriage and Family 74 (October 2012): 913 – 930 913 DOI:10.1111/j.1741-3737.2012.01011.x

914 Journal of Marriage and Family

under averaged 1.51, with almost 40% of youth living with one sibling, about 25% living with two siblings, and over 15% living with 3 or more siblings. Given changing U.S. demographics, it is important to note that these data also revealed variability in sibship size across racial/ethnic groups, with Asian (M = 1.41) and White (M = 1.49) youth having fewer siblings and African American (M = 1.64) and Hispanic youth (M = 1.68) growing up with more siblings. Divorce, remarriage, and multipartner fertility patterns also have had implications: In 2010, more than 10% of households with children included step- or adoptive siblings.

In the face of their ubiquity and potential for influence, however, sibling relationships have been relatively neglected by researchers study- ing close relationships and by family scholars, in particular. Our search of the 1990 – 2011 psycho- logical and sociological abstracts for ‘‘sibling and relation or relationships,’’ for example, yielded 741 citations. In contrast, the counts were 33,990 citations for ‘‘parent or parenting,’’ 8,685 citations for ‘‘marriage or marital relation- ship or marital relation,’’ and 5,059 citations for ‘‘peer relations or peer relationships or friend- ships.’’ Drilling down to the abstracts of the major family journals between 1990 and 2011 and focusing on the neonatal through adolescent periods yielded citation counts of 41 articles in the Journal of Marriage and Family, 18 articles in Family Relations, 21 articles in the Journal of Family Issues and 131 articles in the Jour- nal of Family Psychology with the term sibling in the abstract; only about one third of these articles, however, focused directly on sibling relationships.

Given their relative neglect, the overarching goal of this article is to stimulate interest of family scholars in sibling relationships by portraying the centrality of siblings in family life and sibling influences on child and adolescent development. In so doing we also aim to illuminate the ways in which the study of sibling relationships and dynamics can inform our understanding of how families operate as social and socializing systems. Our review is divided into four sections. First, to introduce family scholars who are new to the field to research on siblings, we begin with an overview of the theoretical traditions and early studies that provide the foundation for contemporary research. This early work was aimed primarily at two topics: (a) factors that shape sibling

relationship qualities and (b) sibling influences on one another’s development. In the second and third sections of this article, we review research conducted between 1990 and 201l on these two topics. In the fourth and final section, we take stock of what we have learned to date about this primary family relationship and make recommendations for future research directions.

FOUNDATIONS OF RESEARCH ON SIBLING RELATIONSHIPS AND INFLUENCES

From its inception, research on siblings has been grounded in a range of disciplinary perspectives. Below we consider five traditions that continue to shape the field. We note, however, that a challenge for sibling relationship researchers is to better integrate concepts and methods toward an interdisciplinary approach to studying sibling relationships.

Sociological and Social Psychological Approaches

One early line of research focused on the significance of sibling structure variables. From this perspective, siblings’ position in the family gives rise to social psychological processes, with lifelong implications for individual development and adjustment (Irish, 1964). Interest in birth order and its impact on achievement emerged in the late 1800s, with Galton’s (1874) analysis of British scientists. Galton concluded that the overrepresentation of firstborns in science leadership was due to the rights and responsibilities conferred on them by laws and mores around primogeniture. As we describe later in this article, scholars from other traditions, such as Adler’s ethological/analytic perspective, also highlighted birth order effects but targeted social and psychological processes, such as firstborns’ dethronement and parents’ tendency to overindulge younger siblings, to explain birth order differences in siblings’ personality and psychological adjustment (Ansbacher & Ansbacher, 1956).

Beginning in the 1950s, sibling gender constellation became a focus (Brim, 1958; Koch, 1960). Findings from a study of 350 five- and six-year-olds, published in a series of monographs and articles, anticipated tenets of social learning theory in demonstrating that higher status, older siblings tended to be more influential models and that model similarity

Sibling Relationships 915

(i.e., same-gender siblings) enhanced a model’s impact. An important insight from this work was that sibling gender constellation effects emerged not only via parent-driven dynamics such as gendered differential treatment but also from siblings’ direct experiences with one another.

A third structure factor was sibship size, in particular its role in achievement. One early perspective that remains influential held that siblings dilute resources available to individual children and thereby limit their achievement (Blake, 1981), and population studies (Blau & Duncan, 1965) found evidence of sibship size effects on education and occupation attainment. A second, confluence model (Zajonc & Markus, 1975) held that families’ overall intellectual climate is a function of its age distribution as determined by number of children, age spacing between them, and children’s corresponding opportunities to teach and be taught by siblings.

A limitation of work on structural variables that persists today, however, is that the social and psychological processes purported to account for sibling constellation effects—such as rivalry, differential treatment, or resource allocation—were inferred on the basis of patterns of sibling outcomes instead of being measured directly. In a series of articles, Furman and Buhrmester (e.g., Buhrmester & Furman, 1990) examined links between structure characteristics and relationship dynamics. Their work showed that structure variables do not fully account for relationship processes and underscored that influence processes should be directly measured.

Psychoanalytic and Ethological Groundings of a Developmental Perspective

A second thread in contemporary research on siblings originated within the psychoanalytic and ethological traditions in the first half of the 20th century. Adler’s theory of individual psychology placed sibling dynamics at the center of family life and personality development (Ansbacher & Ansbacher, 1956). Adler argued that social comparisons and power dynamics in families, in particular sibling rivalry for family resources, were fundamental influences on personality development. He suggested that, as a means of reducing competition, siblings differentiate or de-identify, developing different qualities and choosing different niches. A handful of early studies found evidence consistent with

Adler’s ideas (Grotevant, 1978; Schachter, Shore, Feldman-Rotman, Marquis, & Campbell, 1976) and, as we later discuss, recent research on parents’ differential treatment of siblings also provides support for Adler’s hypotheses about the significance of sibling dynamics in psychological adjustment.

More generally, two themes from psychoana- lytic and ethological perspectives that influenced early sibling research were (a) the significance of early experience and (b) the adaptive functions of social behavior. The ethological tradition also was influential in its emphasis on naturalistic observation methods, an approach adopted by developmental scholars who examined the role of siblings in early socioemotional development (Abramovitch, Corter, & Lando, 1979; Bryant & Crockenberg, 1980; Dunn & Kendrick, 1980). On the basis of this early work, Dunn (1983) concluded that sibling relationships are unique in that they encompass both the complementary interactions typical of adult – child relationships and the reciprocal and mutually influential inter- actions of peers. Further, the frequent and often emotionally charged social exchanges of siblings serve as an impetus for socioemotional develop- ment as young children work to establish their status in the sibling relationship and their niche in the family. Finally, Dunn emphasized moving beyond structural variables to focus on influence processes and stressed the significance of study- ing sibling relationships within the larger family system. Thirty years after Dunn’s article was published, her ideas remain integral to research on sibling relationships and influences.

Learning and Social Learning Perspectives

Learning theories, targeting reinforcement and observational learning, were a third early influ- ence, and they continue to shape the literature on sibling influences. Early findings were consistent with the idea that siblings serve as role models (Brim, 1958). Also consistent were findings from observational studies documenting asymmetri- cal sibling influences, with toddlers imitating their (higher status) older siblings more than the reverse (Abramovitch et al., 1979).

Patterson (1984) broke new ground in his observational research on the sibling relationships of children with conduct disorders. Through analyses of observed reinforcement dynamics, Patterson concluded that sibling relationships can serve as a training ground for

916 Journal of Marriage and Family

aggression when siblings become involved in coercive cycles wherein escalation of negative behavior is rewarded by one partner giving in to the other’s demands. A key contribution of this work was that sibling influence processes were directly observed and measured, and Patterson’s insights continue to motivate contemporary research on siblings’ influences on risky behavior.

Contributions From Behavior Genetics

Studies in this tradition generally treat data on siblings as a methodological tool, comparing siblings of differing degrees of biological relat- edness to draw inferences about the relative roles of genes and environment in development. Such findings are not relevant to understanding sibling relationships, but behavior geneticists’ insights into the significance of the nonshared environment pointed to the potential significance of sibling influences in such forms as siblings’ position in the family structure, parents’ differ- ential treatment of siblings, and asymmetrical sibling interactions (Rowe & Plomin, 1981). Although the nonshared environment is not directly measured in most behavioral genetics research, Plomin and Daniels’s (1987) seminal article ‘‘Why are children in the same family so different from one another?’’ motivated new attention to these differentiation processes by sibling researchers.

Cross-Cultural Perspectives

Using ethnographic methods, cultural anthro- pologists have long highlighted the ubiquity of siblings in the lives of children and fami- lies (Whiting & Whiting, 1975). Research in this tradition aims to identify cross-cultural universals in social patterns and uncover the ecological bases of cultural differences. Sum- marizing results from work beginning in the 1950s, Weisner (1989) noted four cultural uni- versals in sibling relationships: (a) Structural characteristics provide a metric for comparison, and although cultures differ in the emphasis they place on them, these characteristics have implications ranging from their effects on fam- ily dynamics to their effects on cultural beliefs; (b) siblings are common companions growing up and share a family history; (c) in child- hood, siblings are ubiquitous across all primate species; and (d) cultures imbue sibling roles and

relationships with meaning because ‘‘siblings always matter’’ (p. 14).

Cross-cultural research emphasized the care- giving responsibilities of older siblings and the hierarchical structure of sibling roles in non-Western societies as well as cultural dif- ferences in dynamics such as rivalry and compe- tition (Nuckolls, 1993; Weisner, 1989). Weisner pointed to subsistence demands in the devel- opment of sibling dynamics, including sibling residence and inheritance patterns. In daily life, social institutions structure siblings’ roles and relationships, which in turn shape and reinforce cultural beliefs about siblings. Weisner also contrasted kin-focused societies, wherein sib- ling relationships serve as the ‘‘moral ideals,’’ with North American families, whose social institutions fail to promote sibling bonds and responsibilities after adolescence. Nonetheless, even in the Western world, elements of the moral ideal of sisterhood (‘‘Sisterhood is powerful’’) and brotherhood (‘‘He’s not heavy; he’s my brother’’) persist.

Weisner (1989) argued that cross-cultural analyses of sibling relationships provide insights into what is universal in human experience and into ecological factors that promote differences in sibling bonds across place and time. This tradition provides a foundation for emerging research on siblings from racial/ethnic minority groups within the United States that is beginning to examine cultural values and practices that explain variability in sibling dynamics and influences.

SOURCES OF VARIATION IN SIBLING RELATIONSHIPS

We turn now to research on factors that shape sibling relationship dynamics, ranging from characteristics of siblings themselves to the family and cultural contexts within which they are embedded. We also consider recent intervention research aimed at designing and evaluating programs that promote positive sibling relationships. As will be evident, much of this work is built on the theoretical perspectives we have just reviewed.

Role of Child Characteristics in Sibling Relationships

Early research on structural factors inferred social processes from status characteristics such

Sibling Relationships 917

as gender constellation and age spacing, and an important advance is research that goes beyond status characteristics to directly mea- sure siblings’ personal qualities in an effort to understand their impact on sibling ties. One line of work examined siblings’ temperament (Stoneman & Brody, 1993) showing that dif- ficult temperaments, in particular, were linked to sibling relationship difficulties. Later stud- ies tested temperament as a moderator of links between family conditions and sibling relation- ships, suggesting that siblings’ characteristics could exacerbate the effects of stressful family circumstances on sibling ties (Stoneman, Brody, Churchill & Winn, 1999). The latter work also highlighted the role of contextual characteris- tics in sibling relationships, a topic to which we return later.

Child effects also were evident in research on families with children who had a disability or a chronic illness. Research comparing sibling relationships and child adjustment in families with versus without a child with a disability or chronic illness revealed two patterns. First, dyads with a disabled or ill sibling consistently displayed more warmth and positive affect than typical-only dyads (Stoneman, 2001). Second, typical siblings of disabled or ill children had a slightly elevated risk of adjustment problems (Sharpe & Rossiter, 2002). This research tended to be grounded in a deficit model that assumed siblings of atypical youth were at risk (Levy- Wasser & Katz, 2004). Few studies included indices of positive adjustment, but the ones that did showed that there also can be benefits of growing up with a sibling with a disability or illness (Mandelco, Olsen, Dyches, & Marshall, 2003; McHale & Harris, 1992). This work implies that an atypical sibling may make for greater variability in children’s adjustment and that the conditions under which children adjust in more positive or negative ways are an important target for research.

Such insights come from research designs that move beyond group comparisons of adjustment outcomes to examine the processes—such as coping styles or family supports—that explain within-group variability among children with atypical siblings (McHale & Harris, 1992). Longitudinal research also is needed. Knott, Lewis, and Williams (2007) provided a rare picture of the development of sibling relationships of children with autism and Down syndrome. Such studies can illuminate how these

relationships evolve as the typical sibling takes on a more parentlike role, an important issue given parents’ concerns about who will care for the child with a disability when they themselves no longer can (McHale & Harris).

Family Influences on Sibling Relationships

Studying how sibling relationships are embed- ded within families advances our understand- ing of both sibling relationships and families as social systems. Although not traditionally applied to study of sibling relationships, a family systems perspective directs attention to the inter- dependence among the subsystems that comprise families (Minuchin, 1985) and provides an over- arching framework for examining how marital and parental subsystems are linked to sibling relationships. With respect to the marital sub- system, a meta-analysis that included eight studies on marital – sibling relationship associ- ations revealed that sibling relationships were more positive in divorced as compared with always-married families (Kunz, 2001). Other research showed, however, that sibling con- flict and negativity were higher in divorced and separated versus married families (Noller, Con- way, & Blakeley-Smith, 2008), and higher in single-parent versus stepparent and married fam- ilies (Deater-Deckard, Dunn, & Lussier, 2002). Inconsistent findings may be due to the dimen- sions of sibling relationships examined. Noller et al. classified siblings on the basis of the combi- nation of positivity and negativity and found that ‘‘affect intense’’ sibling relationships, character- ized by both high positivity and high negativity, were overrepresented in divorced and separated families as compared with married families. An important insight here is that understanding sib- ling dynamics requires simultaneous attention to multiple dimensions of the relationship.

Accumulating research also suggests that marital and family processes, such as spousal conflict, coparenting, and parenting behaviors, are better predictors of sibling relationship qual- ities than is family status (O’Connor, Hether- ington, & Reiss, 1998). Findings have generally been consistent with a spillover process, such that hostility and conflict in the marital subsys- tem and negativity in parent – child relationships are linked to sibling conflict (Kim, McHale, Osgood, & Crouter, 2006) and violence (Hoff- man, Kiecolt, & Edwards, 2005). Negativity in the parent – child relationship also was shown

918 Journal of Marriage and Family

to mediate links between marital and sibling subsystem dynamics (Stocker & Youngblade, 1999). Some youth may compensate for fam- ily negativity (e.g., in their parents’ marriage), however, by forming close sibling relationships, which in turn protect youth from adjustment problems (Jenkins, 1992; Kim et al.; Milevsky & Levitt, 2005). An important step is to iden- tify the conditions under which spillover versus compensatory processes emerge.

Family systems influences on sibling rela- tionships also have been studied via mothers’ and fathers’ differential treatment of siblings. Systemic family influences are evident in inves- tigations of mother – father patterns of differen- tial treatment and their implications for siblings (Kan, McHale, & Crouter, 2008; Solmeyer, Kil- loren, McHale, & Updegraff, 2011; Volling & Elins, 1998). This work suggests that incongru- ence between mothers’ and fathers’ differential treatment, such that one parent shows preferen- tial treatment toward one sibling and the other does not, may mark a parent – child coalition or breakdown in coparenting that is associ- ated with negative sibling and marital dynamics and poorer adjustment in both siblings. This work also exemplifies how including siblings in research on families allows researchers to cap- ture novel dynamics and illuminate how families operate as systems.

Sociocultural Factors in Sibling Relationships

Substantial variability in the cultural and fam- ily settings in which children’s and adolescents’ lives are embedded underscores the need to represent these diverse contexts in efforts to understand variations in sibling relationships. The rapid growth of ethnic minority and immi- grant populations (U.S. Census Bureau, 2011), underscores the need for greater attention to sibling dynamics in these groups. The litera- ture provides a foundation for understanding sibling dynamics among at-risk ethnic minority youth, but research on normative processes in ethnic minority youths’ sibling relationships and sources of within-culture variation is rare.

Studies of families in challenging circum- stances highlight the unique contributions of siblings to ethnic minority youths’ adjustment. For example, longitudinal data showed that the risk of teenage pregnancy increased fourfold for the younger sisters of Latina and African American adolescent mothers and that having

an older sister who became a parent before age 20 posed a substantially greater risk than having a mother who became pregnant during adoles- cence (East, Reyes, & Horn, 2007). Among poor, rural, African American families, older siblings’ problem behaviors and attitudes were signifi- cantly linked to their younger siblings’ conduct problems (Brody, Ge, et al., 2003).

Much less is known about the ways siblings contribute to one another’s positive development in ethnic minority families. One exception is a longitudinal study conducted by Brody, Kim, Murry, and Brown (2003), which showed that, in rural, African American, single-parent families, older siblings’ social and cognitive competence explained changes in younger siblings’ competencies via their self-regulation. How siblings promote positive development among ethnic minority youth in both high- and low-risk settings is an important direction for future research.

Other studies complement cross-cultural work (Nuckolls, 1993), using ethnic-homoge- neous research designs to illuminate sources of within-group variability in sibling processes. An advantage of ethnic-homogeneous designs is that researchers can target cultural practices and values specific to a cultural group. For example, familism and simpatı́a values in Mexican American families (Gamble & Modry- Mandell, 2008; Killoren, Thayer, & Updegraff, 2008; Updegraff, McHale, Whiteman, Thayer, & Delgado, 2005) and spirituality and ethnic identity in African American families (McHale, Whiteman, Kim, & Crouter, 2007) were linked to more positive sibling relationships. In contrast to ethnic-comparative designs, in which inferences about the role of culture are made on the basis of patterns of group differences, ethnic- homogeneous designs allow for direct tests of the role of cultural processes in sibling dynamics.

Sibling Relationship-Focused Interventions

Sibling relationships can be shaped deliber- ately in intervention programs designed to pro- mote positive and reduce negative dynamics. Although siblings have been largely overlooked in family-based prevention and intervention programs, targeting sibling relationships can provide a less stigmatizing entrée into fami- lies than focusing on parent – child or marital relationship problems (Feinberg, Solmeyer, & McHale, 2012). Defining the role of siblings in

Sibling Relationships 919

interventions broadly, current work falls into three areas: (a) interventions that target sib- lings of at-risk youth; (b) family-based programs whose effects cross over to benefit the siblings of targeted youth; and (c) programs designed to alter sibling relationships via changes in parents’ or siblings’ behaviors, skills, and cognitions.

In recognition of the potential family system effects of children’s disabilities and illnesses, some programs have been designed to support their siblings. One community-based program targeting children with chronic health problems and disabilities resulted in increases in siblings’ self-esteem, perceived support, and knowledge of siblings’ illness/disability and in declines in behavior problems (Williams et al., 2003). Equally important are prevention programs for siblings of youth with adjustment problems who are at disproportionate risk for exhibiting similar problems. East, Kiernan, and Chavez (2003) showed that younger sisters of adolescent mothers who participated in a multifaceted prevention program exhibited lower pregnancy and truancy rates compared with girls in the control group.

Effects of family-based programs can also cross over to nontarget siblings. An inter- vention for younger siblings of adjudicated youth found positive effects on nontarget ado- lescent, but not preadolescent, siblings: Ado- lescent siblings in the intervention group, as compared with the control group, showed declines in delinquency and deviant behav- iors (Brotman et al., 2005). These sibling effects were unexpected but suggest that family-based interventions aimed at reduc- ing problem behavior for multiple children in a family may be cost efficient and effective.

Only a few programs directly target sibling relationships, and these generally focus on reducing conflict and aggression (Kramer, 2004). Typically, parents are trained to address young children’s sibling relationship problems. In one study, mothers were taught to serve as mediators of sibling disputes, and the results revealed improvements in children’s conflict resolution, social understanding, and engagement (Siddiqui & Ross, 2004).

Kennedy and Kramer (2008) designed an intervention to promote prosocial sibling rela- tionship skills and reduce problem behaviors. A trial with European American siblings in early and middle childhood demonstrated positive

effects, including enhanced emotional regula- tion and positive sibling relationship ratings postintervention. Feinberg and colleagues’ (e.g., Solmeyer et al., 2010) intervention for mid- dle childhood siblings was aimed at promot- ing social competencies and reducing sibling conflict via an after-school program with inter- spersed family meetings. Preliminary results provided evidence of the program’s effective- ness in improving sibling relationships and youth and parent well-being. In addition to their prac- tical utility, such experimental studies allow for tests of causal hypotheses regarding sibling dynamics that can only be inferred from descrip- tive and correlational research. Testing theory in such translational research is an important direction for work on factors that shape sibling relationships and their influences.

SIBLING INFLUENCES ON DEVELOPMENT AND ADJUSTMENT

In this section, we review research on siblings’ influences on one another’s development. Most of this work has focused on siblings’ direct influences, such as when they shape behavior during everyday interactions, serve as sources of social support, or act as role models. Less attention has been paid to the ways siblings influence one another indirectly in their roles as building blocks of the family structure and through ripple effects of their behavior and experiences throughout the family system. Although family scholars have not focused extensively on siblings, investigators from disciplines including human development, sociology, psychology, and health have paid increasing attention to sibling influences. Because of space limitations, our review is not exhaustive but is directed at showcasing major areas of study. Again, readers will see that much of this work is grounded in the theoretical perspectives we described earlier.

Direct Sibling Influences

Siblings’ extensive contact and companionship during childhood and adolescence—increas- ingly outside the direct supervision of parents or other adults—provides ample opportunity for them to shape one another’s behavior and socioemotional development and adjustment. Most research on direct sibling influences is

920 Journal of Marriage and Family

grounded in developmental or social learning models, suggesting that, by virtue of their everyday involvement, siblings can promote positive development as well as adjustment problems.

Sibling interactions and children’s social- cognitive development. One line of work can be traced to early observational studies of young siblings (Dunn, 1983) and targets sibling interactions as unique opportunities for social – cognitive development. Through their conflicts, for example, siblings can develop skills in perspective taking, emotion understanding, negotiation, persuasion, and problem solving (Brown, Donelan-McCall, & Dunn, 1996; Dunn, 2007; Howe, Rinaldi, Jennings, & Petrakos, 2002). Notably, these competencies extend beyond the sibling relationship and are linked to later social competence, emotion understanding, and peer relationships (Stormshak, Bellanti, Bierman, & The Conduct Problems Prevention Research Group, 1996; Updegraff; McHale, & Crouter, 2002; Youngblade & Dunn, 1995). In adolescence, siblings also contribute to positive developmental outcomes, including prosocial behavior (Brody, Kim, et al., 2003; Whiteman, McHale, & Crouter, 2007), empathy (Tucker, Updegraff, McHale, & Crouter, 1999), and academic engagement (Bouchey, Shoulberg, Jodl, & Eccles, 2010). Although influence processes in adolescence are rarely studied directly, sibling support has been linked to adolescent adjustment (Branje, van Lieshout, van Aken, & Haselager, 2004).

Sibling influences on adjustment problems. Not all of what siblings learn in their exchanges is positive, and an increasing focus in the past two decades has been on sibling influences on adolescents’ risky behavior and adjustment problems. Sibling conflicts in childhood, for example, are associated with concurrent and later deviance, school problems, bullying, substance use, and internalizing symptoms (Bank, Burraston, & Snyder, 2004; Stocker, Burwell, & Briggs, 2002). Much of the work on sibling influences on adjustment problems is grounded in Patterson’s (1984) social learning model, showing that coercive interaction styles learned in the context of sibling conflict extend to aggression with peers (Bank et al., 2004; Criss & Shaw, 2005) and antisocial behaviors (Compton, Snyder, Schrepferman,

Bank, & Shortt, 2003). In addition to providing a setting for practicing coercive behaviors, reinforcing antisocial behaviors such as deviant talk, and colluding to undermine parental authority (Bullock & Dishion, 2002), siblings (especially older ones) provide each other with models of deviant behavior and serve as gatekeepers to delinquent peers and risky activities (Rowe & Gulley, 1992; Windle, 2000). Concordance between siblings’ externalizing and antisocial behaviors during adolescence (Criss & Shaw, 2005; Fagan & Najman, 2003) has been interpreted as evidence of sibling influences, although again, in studies of adolescents, these sibling influence processes are rarely measured directly.

Other work has documented sibling con- cordance in adolescents’ substance use (Fagan & Najman, 2005; Scholte, Poelen, Willemsen, Boomsma, & Engels, 2008; Slomkowski, Rende, Novak, Lloyd-Richardson, & Niaura, 2005). An important methodological advance here is doc- umenting that sibling influences emerge beyond the effects of parents and peers (Fagan & Najman, 2005; Windle, 2000). Some findings suggest that sibling influences are stronger than parental influences and possibly as strong as that of peers (Brook, Whiteman, Gordon, & Brook, 1990). Although sibling similarities in substance use can arise through a variety of mechanisms, including shared genetics and par- enting, twin and adoption studies show that siblings have unique social influences (McGue, Sharma, & Benson, 1996; Rende, Slomkowski, Lloyd-Richardson, & Niaura, 2005; Slomkowski et al., 2005). In addition to social learning, youth shape the environments in which their siblings’ substance use attitudes and behaviors develop. Older siblings also help to create fam- ily norms and expectancies regarding substance use (Epstein, Griffin, & Botvin, 2008), which influence later use. Finally, siblings may expose each other to settings and peer groups in which substance use is accepted. In fact, siblings’ pat- terns of use are more strongly correlated when they share friends (Rende et al., 2005).

Siblings also are similar in their risky sex- ual behaviors, including age at first intercourse (Widmer, 1997) and attitudes about sex and teenage pregnancy (East, 1998; McHale, Bis- sell, & Kim, 2009). In explaining sibling sim- ilarity, researchers invoke family norms and sibling socialization effects (East, 1998), espe- cially social learning (McHale et al., 2009). For

Sibling Relationships 921

example, older siblings may transmit beliefs about sexual activity and childbearing; provide information regarding sexual activities, includ- ing safe sexual practices; and even exert pressure to engage in sexual activities (East, 1998; Kowal & Blinn-Pike, 2004; Widmer, 1997). As a result, younger siblings may become sexually involved at an earlier age. In line with social learn- ing tenets, sibling similarities in risky sexual behaviors are greatest for same-sex siblings and those with warm relationships (McHale et al., 2009) and when siblings share friends (East, 1998). Beyond models and sources of infor- mation, older siblings may play a matchmaker role, introducing their brothers and sisters to partners who are older and possibly more expe- rienced sexually, leading to an increased risk for early sexual activity (Rodgers, Rowe, & Harris, 1992).

Sibling differentiation. Differentiation proc- esses also involve siblings treating one another as sources of social comparison but imply that siblings treat one another as foils, de-identifying from one another by selecting different niches in the family and developing distinct personal qual- ities. In line with Adler’s theory of individual psychology, some work suggests that differ- entiation dynamics help protect siblings from rivalry and jealousy (Schachter et al., 1976; Sul- loway, 1996). Although sibling differentiation is hypothesized to lead to warmer and less conflict- ual sibling relationships, the findings have been mixed (Feinberg, McHale, Crouter, & Cumsille, 2003; Whiteman, Bernard, & McHale, 2010; Whiteman et al., 2007).

Early work on sibling differentiation focused on personality and temperament (Schachter et al., 1976), and more recent studies have shown that differentiation dynamics are prevalent in domains ranging from adjustment (Feinberg & Hetherington, 2000) to social competence and risky behaviors and attitudes (Whiteman et al., 2010). This work is important given that dif- ferentiation processes have not been the focus of research on sibling influences on adjust- ment and that differentiation processes may become increasingly evident in adolescence, when identity development is a salient task. Furthermore, when not measured directly, the strength of sibling influence processes may be underestimated, because some serve to make siblings alike and others serve to make siblings different.

Indirect Sibling Influences

Most current research focuses on direct mech- anisms of sibling influence, but evidence is accumulating on the processes through which siblings indirectly affect one another (McHale et al., 2006). Below we consider siblings’ indi- rect influences via their effects on other family members, on broader family dynamics, and as building blocks of the family structure. Our review reveals that we know far less about sib- lings’ place in such family system dynamics than we do about the sibling dyad per se. This is a direction that is ripe for research.

Learning from experience. A recent line of study suggests that siblings can provide learning opportunities for their parents that have impli- cations for how parents carry out their parental roles. The significance of child effects on par- ents has a long tradition in developmental and family studies, but almost all of this work has focused on children’s dyadic relationships with their parents (McHale et al., 2006). Research that takes sibling dynamics into account has revealed that children also can influence par- ents’ expectations, knowledge, and parenting behavior in ways that have implications for their siblings. Whiteman and Buchanan (2002) found that parents who had experienced an earlier-born child’s transition to adolescence were less likely to expect later-born offspring to exhibit emotional and behavioral problems during this transition. Altered expectations, com- bined with what parents learn through practice, may have important implications: Comparisons of siblings’ relationships with parents at the same chronological ages, for example, have shown that parents exhibit more effective par- enting behaviors, including lower conflict and higher levels of warmth and parental knowledge, with secondborn than with firstborn adolescents (Shanahan, McHale, Osgood, & Crouter, 2007; Whiteman, McHale, & Crouter, 2003). We know next to nothing, however, about parents’ learning experiences at other points in family life, such as pregnancy and the transition to parenthood, children’s school transitions, or young adults’ transitions out of the home. A learning-from- experience model suggests that parents may be more efficient and effective at managing par- enthood challenges the second (or third) time around. This model contrasts with the resource dilution model, described below, which holds that each successive child results in lowered

922 Journal of Marriage and Family

family investments, with negative implications for later-born children.

Furthermore, what parents learn from their experiences may not always have positive implications. East (1998) argued that teenage childbearing by an older sister may increase the chances of a younger sister also becoming a teen parent when mothers come to believe that they are unable to control their daughters’ sexual activities and give up on parenting efforts toward other daughters. Helping parents make the most of their learning experiences may be a fruitful focus for parent education and family interventions.

Parents’ differential treatment. As Adler argued, children indirectly shape their broth- ers’ and sisters’ characteristics and behaviors by serving as sources of social comparison, and from a very young age they attend to the ways in which their parents treat them relative to their siblings (Ansbacher & Ansbacher, 1956). A body of work now shows that differential treatment, such as in privileges, discipline, and parent – child conflict and affection, are linked to less positive sibling relationships (Brody & Stoneman, 1994; Shanahan, McHale, Crouter, & Osgood, 2008), poorer adjustment, and adjust- ment differences between siblings, with disfa- vored children generally showing poorer adjust- ment (Coldwell, Pike, & Dunn, 2008; Conger & Conger, 1994; McGuire, Dunn, & Plomin, 1995). Some research indicates that the implica- tions of differential treatment are evident beyond the effects of parent – child dyadic relationship quality (Feinberg & Hetherington, 2001; Shana- han et al., 2008). The negative implications of differential treatment, however, are moderated by youths’ understanding of parents’ reasons for differential treatment, their perceptions of its fairness, and their family values (Kowal & Kramer, 1997; McHale, Updegraff, Shanahan, Crouter, & Killoren, 2005).

Resource dilution. Siblings are building blocks of the family structure, and their constellation has implications for family dynamics. Grounded in ideas about the role of social and eco- nomic capital in youth development, decades of research tested the role of sibling constel- lation factors in intelligence and achievement. The resource-dilution model has considerable conceptual appeal, moving research on family influences beyond the sibling or parent – child

dyad to target the larger family system (Downey, 2001; Rodgers, 2001; Steelman, Powell, Werum, & Carter, 2002). From this perspective, how- ever, sibling influences are negative. On the basis of a review of hundreds of studies, mostly conducted in the United States, Steelman et al. concluded that ‘‘the evidence of a nega- tive relationship between size of sibling group and academic success, at least in the United States . . . has been virtually unequivocal’’ (p. 248).

Debate continues, however, regarding the causal effects of sibling constellation in achieve- ment. For instance, instead of large sib- ships causing lower achievement, the alterna- tive, admixture hypothesis proposes that lower achieving parents have more children (Rodgers, 2001). Sibship size effects also are malleable: National comparisons show that family size effects are not evident in countries with strong family supportive policies (Park, 2008); histori- cal analyses reveal within-country changes over time in these effects that are correlated with changes in social policies and economic con- ditions (Maralani, 2008); and even within the United States, sibship size effects on achieve- ment are not evident in Mormon families, which emphasize the importance of family (Downey, 2001). Most significantly, although the resource- dilution model proposes that family size sets into motion family processes that are the proximal causes of youth achievement, as in other lines of research on siblings those processes have rarely been measured directly (see Downey, 1995, and Strohschein, Gauthier, Campbell, & Kleparchuk, 2008, for exceptions).

CONCLUSIONS

Our review reveals that early writers’ efforts to motivate research on siblings have borne fruit in the form of a relatively small literature on siblings’ place in family structure, their role in family dynamics, and their influences on child and adolescent development. In addition, the past two decades have seen advances in the methodological sophistication of sibling research, including attention to both members of the dyad, some efforts to directly measure social and socializing processes involving siblings, consideration of the larger contexts in which siblings are embedded, and the study of sibling relationships and influences using experimental and longitudinal designs. From this work we

Sibling Relationships 923

can draw several conclusions about sibling relationships and influences in childhood and adolescence, although there remain important directions for future research. We address these two topics in this final section of this review.

Lessons Learned From the Literature on Sibling Relationships

Taken together, theory and research on siblings reveal first that sibling relationships are shaped by individual, family, and extrafamilial forces. Although siblings are ubiquitous in the lives of children and adolescents, the characteristics of their relationships and roles vary considerably across time and place, with corresponding implications for the nature and power of sibling influences on youth and families (Updegraff, McHale, Killoren, & Rodriguez, 2010; Weisner, 1989).

A second insight from the extant literature is that sibling influences on youth development and adjustment are unique in the sense that evidence of sibling influences emerges even after the effects of other significant relation- ships are taken into account (Brook et al., 1990; Windle, 2000). The power of sibling influences may stem from the multifaceted—and, in some cases, unique—social and psychological pro- cesses through which siblings are thought to exert their effects (Dunn, 2007). A related les- son is that studying sibling influences directs attention to novel social, psychological, and fam- ily processes—such as sibling de-identification, parents’ learning from experience, and the opera- tion of family coalitions—that have been largely overlooked in empirical research on families. Most family research has been conducted with the seeming assumption that studying one child in a family is sufficient for understanding how families operate and how they influence individ- ual development and adjustment. Research on siblings has revealed, however, that two individ- uals from the same family are often as different as unrelated individuals (Plomin & Daniels, 1987), suggesting that, in failing to incorporate siblings in their investigations, family scholars may be missing important pieces of the family puzzle.

In addition to the theoretical primacy of parent – child and marital bonds (Irish, 1964), methodological complexities may be a deterrent to incorporating siblings into family research: Identifying and recruiting a sample that takes

sibling structure variables (age spacing, gender constellation, birth order, and sibship size) into account is an expensive and difficult task, measuring the individual and family relationship characteristics of more than one child in a family increases the demands of data collection, and the field lacks a toolkit for quantitative analysis of triadic and larger systemic family processes. In the face of such deterrents, however, our review suggests that studying more than one child in a family can provide a window into how families operate as social and socializing systems. Despite its conceptual appeal, empirical research on families as systems is rare. This may be in part because systems processes are difficult to measure and in part because propositions regarding causal processes within family systems theory are limited. Including siblings in family research opens up opportunities to move beyond dyadic relationships to examine more complex, higher order processes, such as parents’ differential treatment of two siblings or mothers’ and fathers’ coparenting of siblings, and to test hypotheses about family processes derived from a range of theoretical perspectives.

Directions for Future Research

For family scholars who pursue research on sibling relationships and influences, our review also reveals several directions for future research. Foremost is the necessity of direct measurement of hypothesized influence processes. In most research, sibling influence processes are inferred from patterns of sibling outcomes, such as when sibling concordance is interpreted as evidence of social learning (Criss & Shaw, 2005; Slomkowski et al., 2005). Given that some sibling influence processes operate to make siblings alike and other processes operate to make siblings different from one another (Whiteman et al., 2007), measuring only patterns of outcomes may underestimate sibling influences. Testing mediational models to document the processes that explain sibling similarities and differences is an important part of this agenda.

Direct examination of the processes through which siblings influence the larger family system also is needed. Several lines of work suggest that siblings have implications for one another’s family experiences, but again, the underlying processes, such as whether parents learn from

924 Journal of Marriage and Family

experience (Whiteman et al., 2003) or whether siblings dilute family resources (Downey, 2001), require direct assessment. Expanding these lines of research to examine the implications of developmental transitions (e.g., a firstborn’s entry into formal schooling or move out of the home) for siblings and sibling dynamics may help to illuminate sibling influences on their families (Volling, 2012).

Another important direction is toward greater integration of the diverse theoretical and disci- plinary approaches that undergird the study of sibling relationships. Our review reveals that research conducted in the past two decades has been grounded in theoretical traditions and associated methodologies that are largely com- plementary. Increasing appreciation of interdis- ciplinary scholarship, however, highlights what researchers can learn from theories, methods, and knowledge bases derived from different fields of study.

The field also would benefit from exami- nations of the increasingly diverse family and larger sociocultural contexts in which siblings interact and exert their influences. Most of the research we reviewed here draws from samples of European and European American families with singleton biological siblings. Demographic changes in rates of cohabitation, marriage, divorce, and multiple births have resulted in substantial diversity in the family contexts in which siblings’ relationships are embedded. Comparative designs document differences in sibling relationship qualities as a function of family type (e.g., Deater-Deckard et al., 2002; Noller et al., 2008) but, as we have suggested, a process-oriented approach is necessary for illuminating how and why sibling relation- ships develop differently in different family contexts.

Relatedly, the growing immigrant popula- tion in the United States (U.S. Census Bureau, 2011) necessitates the study of sibling relation- ships and their influences in diverse groups. Scholarship on siblings in African American and Latino families has emerged in the last decade, but our knowledge of sibling relation- ships in their sociocultural contexts remains limited. As in the larger field of research on ethnic minority families, researchers should investigate siblings’ role in positive develop- ment, examine dyads from a range of socio- economic circumstances, and study how sibling relationships and influences unfold over time.

Using both ethnic-homogeneous and ethnic- comparative designs also will increase our understanding of within- and between-group variability in sibling relationship dynamics (McLoyd, 1998).

Building on these recommendations for a focus on process and context, and consistent with an ecological perspective (Bronfenbrenner, 1979), another step is to examine the inter- play among sibling structure characteristics, relationship processes, and larger family and sociocultural contextual conditions. Early efforts to match sibling structure to relational processes revealed that structure explained process nei- ther consistently nor completely (Buhrmester & Furman, 1990). A solution was to highlight the significance of social processes, but this approach leaves open the question of whether structural factors condition the effects of pro- cess. Relatedly, as we have noted, siblings are building blocks of family structure, yet beyond research on sibship size almost nothing is known about family-wide constellations of sibling rela- tionships and roles, including how experiences in one sibling relationship influence dynamics in another, or moderate their impact on devel- opment. Given that about 40% of U.S. children live in households with more than one sibling, studying sibling relationships at the family level to capture multiple dyads is crucial for under- standing how families operate.

Our final recommendation is to strengthen the theoretical and empirical understanding of sib- ling relationship and influence processes through translational research. Consistent with the neglect of sibling relationships by family schol- ars, prevention and intervention researchers have paid scant attention to siblings (Feinberg et al., 2012; Kramer, 2004). Experimental trials of sibling-focused interventions designed to alter sibling relationship qualities such as conflict resolution (Siddiqui & Ross, 2004) or emotion regulation (Kennedy & Kramer, 2008) have pro- vided opportunities to study the causal effects of sibling dynamics on youth adjustment and larger family processes (Feinberg et al., 2012). Such experimental tests of models of sibling influence have both theoretical and practical implications.

Retrospect and Prospect

In his early efforts to motivate research on siblings, Irish (1964) noted that most of

Sibling Relationships 925

the literature on families ‘‘would lead one to conclude that parents rear their children one at a time—or in separate compartments’’ (p. 287). In the face of the ubiquity of siblings and sibling relationships in family life and their documented significance for family dynamics and development and adjustment during childhood and adolescence, sibling research still remains outside the mainstream of scholarship on families. We have argued that incorporating information about multiple siblings and their relationships into research on families can provide new insights about family dynamics and about how families operate as social and socializing systems. We hope that the next generation of family scholars finds our case convincing!

NOTE

We acknowledge support from the National Institute for Child Health and Human Development (Grant R01- HD32336, Susan M. McHale and Ann C. Crouter, Co- Principal Investigators [PIs], and Grant R01HD39666, Kimberly Updegraff, PI); from the National Institute on Alcohol Abuse and Alcoholism (Grant R21-AA017490, Shawn D. Whiteman, PI); and from the Population Research Center at The Pennsylvania State University, which is supported by an infrastructure grant (R24-HD041025) from the National Institutes of Health. We thank Susan Doughty and Cynthia Mitchell for their assistance in this article’s preparation.

REFERENCES

Abramovitch, R., Corter, C. M., & Lando, B. (1979). Sibling interaction in the home. Child Develop- ment, 50, 997 – 1003. doi:10.2307/1129325

Ansbacher, H. L., & Ansbacher, R. R. (1956). The individual psychology of Alfred Adler. New York: Basic Books.

Bank, L., Burraston, B., & Snyder, J. (2004). Sibling conflict and ineffective parenting as predictors of adolescent boys’ antisocial behavior and peer difficulties: Additive and interactional effects. Journal of Research on Adolescence, 14, 99 – 125. doi:10.1111/j.1532-7795.2004.01401005.x

Blake, J. J. (1981). Family size and the qual- ity of children. Demography, 18, 421 – 442. doi:10.2307/2060941

Blau, P. M., & Duncan, O. D. (1965). Some prelimi- nary findings on social stratification in the United States. Acta Sociologica, 9, 4 – 24.

Bouchey, H. A., Shoulberg, E. K., Jodl, K. M., & Eccles, J. S. (2010). Longitudinal links between older sibling features and younger siblings’ aca- demic adjustment during early adolescence. Jour- nal of Educational Psychology, 102, 197 – 211. doi:10.1037/aa0017487

Branje, S. J., van Lieshout, C. F., van Aken, M. A., & Haselager, G. J. (2004). Perceived support in sibling relationships and adolescent adjustment. Journal of Child Psychology and Psychiatry, 45, 1385 – 1396. doi:10.1111/j.1469-7610.2004. 00332.x

Brim, O. G. (1958). Family structure and sex role learning by children: A further analysis of Helen Koch’s data. Sociometry, 21, 1 – 16. doi:10.2307/ 2786054

Brody, G. H., Ge, X., Kim, S. Y., Murry, V. M., Simons, R. L., Gibbons, F. X., Gerrard, M., & Conger, R. D. (2003). Neighborhood disadvantage moderates associations of parenting and older sib- ling problem attitudes and behavior with conduct disorders in African American children. Journal of Consulting and Clinical Psychology, 71, 211 – 222. doi:10.1037/0022-006X.71.2.211

Brody, G. H., Kim, S., Murry, V. M., & Brown, A. C. (2003). Longitudinal direct and indirect pathways linking older sibling competence to the develop- ment of younger sibling competence. Developmen- tal Psychology, 39, 618 – 628. doi:10.1037/0012-1 649.39.3.618

Brody, G. H., & Stoneman, Z. (1994). Sibling rela- tionships and their association with parental differ- ential treatment. In E.M. Hetherington, D. Reiss, & R. Plomin (Eds.), Separate social world of sib- lings: The impact of the nonshared environment on development (pp. 129 – 142). Hillsdale, NJ: Erlbaum.

Bronfenbrenner, U. (1979). The ecology of human development: Experiments by nature and design. Cambridge, MA: Harvard University Press.

Brook, J. S., Whiteman, M., Gordon, A. S., & Brook, D. W. (1990). The role of older brothers in younger brothers’ drug use viewed in the context of parent and peer influences. Journal of Genetic Psychology, 151, 59 – 75. doi:10.1080/ 00221325.1990.9914644

Brotman, L. M., Dawson-McClure, S., Gouley, K. K., McGuire, K., Burraston, B., & Bank, L. (2005). Older siblings benefit from a family-based preventive intervention for preschools at risk for conduct problems. Journal of Family Psychology, 19, 581 – 591. doi:10.1037/0893-3200.19.4.581

Brown, J. R., Donelan-McCall, N., & Dunn, J. (1996). Why talk about mental states? The significance of children’s conversations with friends, siblings, and mothers. Child Development, 67, 836 – 849. doi:10.1111/j.1467-8624.1996.tb01767.x

Bryant, B., & Crockenberg, S. (1980). Correlates and dimensions of prosocial behavior: A study of female siblings with their mothers. Child Development, 51, 529 – 544. doi:10.2307/1129288

Buhrmester, D., & Furman, W. (1990). Perceptions of sibling relationships during middle childhood and adolescence. Child Development, 61, 1387 – 1398. doi:10.1111/j.1467-8624.1990.tb02869

926 Journal of Marriage and Family

Bullock, B. M., & Dishion, T. J. (2002). Sibling collusion and problem behavior in early ado- lescence: Toward a process model for family mutuality. Journal of Abnormal Child Psychology, 30, 143 – 153. doi:10.1023/A:1014753232153

Coldwell, J., Pike, A., & Dunn, J. (2008). Maternal dif- ferential treatment and child adjustment: A multi- informant approach. Social Development, 17, 596 – 612. doi:10.1111/j.1467-9507.2007.00440.x

Compton, K., Snyder, J., Schrepferman, L., Bank, L., & Shortt, J. W. (2003). The contribution of parents and siblings to antisocial and depressive behavior in adolescents: A double jeopardy coercion model. Development and Psychopathology, 15, 163 – 182. doi:10.1017/S0954579403000099

Conger, K., & Conger, R. D. (1994). Differential parenting and change in sibling differences in delinquency. Journal of Family Psychology, 8, 287 – 302. doi:10.1037/0893-3200.8.3.287

Criss, M. M., & Shaw, D. S. (2005). Sibling relationships as contexts for delinquency training in low-income families. Journal of Family Psychology, 19, 592 – 600. doi:10.1037/0893- 3200.19.4.592

Deater-Deckard, K., Dunn, J., & Lussier, G. (2002). Sibling relationships and social-emotional adjustment in different family contexts. Social Development, 11, 571 – 590. doi:10.1111/1467- 9507.00216

Downey, D. B. (1995). When bigger is not better: Family size parental resources and children’s educational performance. American Sociological Review, 60, 746 – 761. doi:10.2307/2096320

Downey, D. B. (2001). Number of siblings and intel- lectual development: The resource dilution expla- nation. American Psychologist, 56, 497 – 504. doi:10.1037/0003-066X.56.6-7.497

Dunn, J. (1983). Sibling relationships in early childhood. Child Development, 54, 787 – 811. doi:10.2307/1129886

Dunn, J. (2007). Siblings and socialization. In J. E. Grusec & P. D. Hastings (Eds.), Hand- book of socialization: Theory and research (pp. 309 – 327). New York: Guilford Press.

Dunn, J., & Kendrick, C. (1980). The arrival of a sibling: Changes in patterns of interaction between mother and first-born child. Journal of Child Psychology and Psychiatry, 21, 119 – 132.

East, P. L. (1998). Impact of adolescent childbear- ing on families and younger siblings: Effects that increase younger siblings’ risk for early preg- nancy. Applied Developmental Science, 2, 62 – 74. doi:10.1207/s1532480xads0202_1

East, P. L., Kiernan, E., & Chavez, G. (2003). An evaluation of California’s adolescent sibling pregnancy prevention program. Perspectives on Sexual and Reproductive Health, 35, 62 – 70. doi:10.1363/3506203

East, P. L., Reyes, B. T., & Horn, E. J. (2007). Association between adolescent pregnancy and a family history of teenage births. Perspectives on Sexual and Reproductive Health, 29, 108 – 115. doi:10.1363/3910807

Epstein, J. A., Griffin, K. W., & Botvin, G. J. (2008). A social influence model of alcohol use for inner-city adolescents: Family drinking, perceived drinking norms and perceived social benefits of drinking. Journal of Studies on Alcohol and Drugs, 69, 397 – 405.

Fagan, A. A., & Najman, J. M. (2003). Sibling influences on adolescent delinquent behaviour: An Australian longitudinal study. Journal of Adolescence, 26, 546 – 558. doi:10.1016/S0140- 1971(03)00055-1

Fagan, A. A., & Najman, J. M. (2005). The relative contributions of parental and sibling substance use to adolescent tobacco, alcohol, and other drug use. Journal of Drug Issues, 35, 869 – 884. doi:10.1177/002204260503500410

Feinberg, M. E., & Hetherington, E. M. (2000). Sib- ling differentiation in adolescence: Implications for behavioral genetic theory. Child Development, 71, 1512 – 1524. doi:10.1111/1467-8624.00243

Feinberg, M. E., & Hetherington, E. M. (2001). Differential parenting as a within-family variable. Journal of Family Psychology, 15, 22 – 37. doi:10.1037/0893-3200.15.1.22

Feinberg, M. E., McHale, S. M., Crouter, A. C., & Cumsille, P. (2003). Sibling differentiation: Sibling and parent relationship trajectories in adolescence. Child Development, 74, 1261 – 1274. doi:10.1111/1467-8624.00606

Feinberg, M. E., Solmeyer, A., & McHale, S. M. (2012). The third rail of family systems: Sib- ling relationships, mental and behavioral health, and preventive intervention in childhood and adolescence. Clinical Child and Family Psychol- ogy Review, 15, 43 – 57. doi:10.1007/s10567-011- 0104-5

Galton, F. (1874). English men of science: Their nature and nurture. London: McMillan. doi:10.5962/bhl.title.26466

Gamble, W. C., & Modry-Mandell, K. (2008). Family relations and the adjustment of young children of Mexican descent: Do family cultural values moderate these associations? Social Development, 17, 358 – 379. doi:10.1111/j.1467 – 9507.2007. 00429.x

Grotevant, H. (1978). Sibling constellations and sex-typing of interests in adolescence. Child Development, 49, 540 – 542. doi:10.2307/1128727

Hoffman, K. L., Kiecolt, K. J., & Edwards, J. N. (2005). Physical violence between siblings: A theoretical and empirical analysis. Journal of Family Issues, 26, 1103 – 1130. doi:10.1177/01925 13X05277809

Sibling Relationships 927

Howe, N., Rinaldi, C. M., Jennings, M., & Petrakos, H. (2002). No! The lambs can stay out because they got cozies! Constructive and destructive sibling conflict, pretend play, and social under- standing. Child Development, 73, 1460 – 1473. doi:10.1111/1467-8624.00483

Irish, D. P. (1964). Sibling interaction: A neglected aspect in family life research. Social Forces, 42, 279 – 288. doi:10.2307/2575529

Jenkins, J. M. (1992). Sibling relationships in disharmonious homes: Potential difficulties and protective effects. In F. Boer & J. Dunn (Eds.), Children’s sibling relationships: Developmental and clinical issues (pp. 125 – 138). Hillsdale, NJ: Erlbaum.

Kan, M., McHale, S. M., & Crouter, A. C. (2008). Interparental incongruence in differential treat- ment of adolescent siblings: Links with marital quality. Journal of Marriage and Family, 70, 466 – 479. doi:10.1111/j.1741-3737.2008.00494.x

Kennedy, D. E., & Kramer, L. (2008). Improv- ing emotion regulation and sibling relationship quality: The more fun with sisters and broth- ers program. Family Relations, 57, 567 – 578. doi:10.1111/j.1741-3729.2008.00523.x

Killoren, S. E., Thayer, S. M., & Updegraff, K. A. (2008). Conflict resolution between Mexican origin adolescent siblings. Journal of Marriage and Family, 70, 1200 – 1212. doi:10.1111/j.1741- 3737.2008.00560.x

Kim, J., McHale, S. M., Osgood, D. W., & Crouter, A. C. (2006). Longitudinal course and family correlates of sibling relationships from childhood through adolescence. Child Development, 77, 1746 – 1761. doi:10.1037/0012-1649.43.4.960

King, M., Ruggles, S., Alexander, J. T., Flood, S., Genadek, K., Schroeder, M. B., Trampe, B., & Vick, R. (2010). Integrated Public Use Micro- data Series, Current Population Survey: Version 3.0 [Machine-readable database]. University of Minnesota, Minneapolis.

Knott, F., Lewis, C., & Williams, T. (2007). Sibling interaction of children with autism: Development over 12 months. Journal of Autism and Developmental Disorders, 37, 1987 – 1995. doi:10.1007/s10803-006-0347-z

Koch, H. (1960). The relation of certain formal attributes of siblings to attitudes held toward each other and toward their parents. Monographs of the Society for Research in Child Development, 25(4, Serial No. 78). doi:10.2307/1165605

Kowal, A., & Blinn-Pike, L. (2004). Sibling influences on adolescents’ attitudes toward safe sex practices. Family Relations, 53, 377 – 384. doi:10.1111/j.0197-6664.2004.00044.x

Kowal, A., & Kramer, L. (1997). Children’s under- standing of parental differential treatment. Child Development, 68, 113 – 126. doi:10.2307/1131929

Kramer, L. (2004). Experimental interventions in sibling relations. In R. D. Conger, F. O. Lorenz, & K. A. S. Wickrama (Eds.), Continuity and change in family relations: Theory, methods, and empirical findings (pp. 345 – 382). Mahwah, NJ: Erlbaum.

Kunz, J. (2001). Parental divorce and children’s interpersonal relationships: A meta-analysis. Jour- nal of Divorce & Remarriage, 34, 19 – 47. doi:10.1300/J087v34n03_03

Levy-Wasser, N., & Katz, S. (2004). The rela- tionship between attachment style, birth order, and adjustment in children who grow up with a sibling with mental retardation. British Jour- nal of Developmental Disabilities, 50, 89 – 98. doi:10.1179/096979504799103921

Mandelco, B., Olsen, S. F., Dyches, T., & Marshall, E. (2003). The relationship between family and sibling functioning in families raising a child with a disability. Journal of Family Nursing, 9, 365 – 396. doi:10.1177/1074840703258329

Maralani, V. (2008). The changing relationship between family size and educational attainment over the course of socioeconomic development: Evidence from Indonesia. Demography, 45, 693 – 717. doi:10.1353/dem.0.0013

McGue, M., Sharma, A., & Benson, P. (1996). Parent and sibling influences on adolescent alcohol use and misuse: Evidence from a U.S. adoption cohort. Journal of Studies on Alcohol, 57, 8 – 18.

McGuire, S., Dunn, J., & Plomin, R. (1995). Maternal differential treatment of siblings and children’s behavioral problems: A longitudinal study. Development and Psychopathology, 7, 515 – 528. doi:10.1017/S0954579400006660

McHale, S. M., Bissell, J., & Kim, J. (2009). Sibling relationship, family, and genetic factors in sibling similarity in sexual risk. Journal of Family Psychology, 23, 562 – 572. doi:10.1037/a0014982

McHale, S. M., & Harris, V. S. (1992). Children’s experiences with disabled and nondisabled sib- lings: Links with personal adjustment and rela- tionship evaluations. In F. Boer & J. Dunn (Eds.), Children’s sibling relationships: Developmental and clinical issues (pp. 83 – 100). Hillsdale, NJ: Erlbaum.

McHale, S. M., Kim, J., & Whiteman, S. D. (2006). Sibling relationships in childhood and adoles- cence. In P. Noller & J. A. Feeney (Eds.), Close relationships: Functions, forms and processes (pp. 127 – 149). New York: Psychology Press.

McHale, S. M., Updegraff, K. A., Shanahan, L., Crouter, A. C., & Killoren, S. E. (2005). Sib- lings’ differential treatment in Mexican American families. Journal of Marriage and Family, 67, 1259 – 1274. doi:10.1037/0012-1649.37.1.115

McHale, S. M., Whiteman, S. D., Kim, J., & Crouter, A. C. (2007). Characteristics and correlates of

928 Journal of Marriage and Family

sibling relationships in two-parent African Amer- ican families. Journal of Family Psychology, 21, 227 – 235. doi:10.1037/0893-3200.21.2.227

McLoyd, V. C. (1998). Changing demographics in the American population: Implications for research on minority children and adolescents. In V. C. McLoyd & L. Steinberg (Eds.), Studying minority adolescents: Conceptual, methodologi- cal, and theoretical issues (pp. 3 – 28). Mahwah, NJ: Erlbaum.

Milvesky, A., & Levitt, M. J. (2005). Sibling sup- port in early adolescence: Buffering and com- pensation across relationships. European Jour- nal of Developmental Psychology, 2, 299 – 320. doi:10.1080/17405620544000048

Minuchin, P. (1985). Families and individual development: Provocations from the field of family therapy. Child Development, 56, 289 – 302. doi:10.2307/1129720

Noller, P., Conway, S., & Blakeley-Smith, A. (2008). Sibling relationships in adolescent and young adult twin and nontwin siblings: Managing competition and comparison. In J. P. Forgas & J. Fitness (Eds.), Social relationships: Cognitive, affective, and motivational processes (pp. 235 – 252). New York: Psychology Press.

Nuckolls, C. W. (1993). An introduction to the study of cross-cultural sibling relations. In C. W. Nuckolls (Ed.), Siblings in south Asia (pp. 19 – 44). New York: Guilford Press.

O’Connor, T. G., Hetherington, E. M., & Reiss, D. (1998). Family systems and adolescent develop- ment: Shared and nonshared risk and protective factors in nondivorced and remarried families. Development and Psychopathology, 10, 353 – 375. doi:10.1017/S0954579498001643

Park, H. (2008). Public policy and the effect of sibship size on educational achievement: A comparative study of 20 countries. Social Science Research, 37, 874 – 887. doi:10.1016/j.ssresearch.2008.03.002

Patterson, G. R. (1984). Siblings: Fellow travelers in coercive family processes. In R. J. Blanchard (Ed.), Advances in the study of aggression (pp. 174 – 214). New York: Academic Press.

Plomin, R., & Daniels, D. (1987). Why are children in the same family so different from one another? Behavioral and Brain Sciences, 10, 1 – 16. doi:10.1017/S0140525X00055941

Rende, R., Slomkowski, C., Lloyd-Richardson, E., & Niaura, R. (2005). Sibling effects on substance use in adolescence: Social contagion and genetic relatedness. Journal of Family Psychology, 19, 611 – 618. doi:10.1037/0893-3200.19.4.611

Rodgers, J. L. (2001). What causes birth order – intelligence patterns? The admixture hypothesis, revived. American Psychologist, 56, 505 – 510. doi:10.1037/0003-066X.56.6-7.505

Rodgers, J. L., Rowe, D. C., & Harris, D. F. (1992). Sibling differences in adolescent sexual behavior:

Inferring process models from family composition patterns. Journal of Marriage and the Family, 54, 142 – 152. doi:10.2307/353282

Rowe, D. C., & Gulley, B. L. (1992). Sibling effects on substance use and delinquency. Criminol- ogy, 30, 217 – 233. doi:10.1111/j.1745-9125.1992. tb01103.x

Rowe, D. C., & Plomin, R. (1981). The importance of nonshared (E1) environmental influences in behav- ioral development. Developmental Psychology, 17, 517 – 531. doi:10.1037/0012-1649.17.5.517

Schachter, F. F., Shore, E., Feldman-Rotman, S., Marquis, R. E., & Campbell, S. (1976). Sibling deidentification. Developmental Psychology, 12, 418 – 427. doi:10.1037/0012-1649.12.5.418

Scholte, R. H. J., Poelen, E. A. P., Willemsen, G., Boomsma, D. I., & Engels, R. C. M. E. (2008). Relative risks of adolescent and young adult alcohol use: The role of drinking fathers, mothers, siblings, and friends. Addictive Behaviors, 33, 1 – 14. doi:10.1016/j.addbeh.2007.04.015

Shanahan, L., McHale, S. M., Crouter, A. C., & Osgood, D. W. (2008). Linkages between parents’ differential treatment, youth depressive symptoms, and sibling relationships. Journal of Marriage and Family, 70, 480 – 494. doi:10.1111/j.1741- 3737.2008.00495.x

Shanahan, L., McHale, S. M., Osgood, D. W., & Crouter, A. C. (2007). Conflict with mothers and fathers from middle childhood through ado- lescence: Within- and between-family compar- isons. Developmental Psychology, 43, 539 – 550. doi:10.1037/0012-1649.43.3.539

Sharpe, D., & Rossiter, L. (2002). Siblings of children with a chronic illness: A meta-analysis. Journal of Pediatric Psychology, 27, 699 – 710. doi:10.1093/jpepsy/27.8.699

Siddiqui, A., & Ross, H. S. (2004). Mediation as a method of parent intervention in children’s disputes. Journal of Family Psychology, 18, 147 – 159. doi:10.1037/0893-3200.18.1.147

Slomkowski, C., Rende, R., Novak, S., Lloyd- Richardson, E., & Niaura, R. (2005). Sibling effects on smoking in adolescence: Evidence for social influence from a genetically informative design. Addiction, 100, 430 – 438. doi:10.1111/j.13 60-0443-.2004.00965.x

Solmeyer, A., Feinberg, M. E., Sakuma, K., Hostetler, M., McHale, S. M., & Jones, D. (2010, November). Siblings are Special: A universal program to promote sibling relationships and prevent substance use in early adolescents. Paper presented at the 72nd Annual Conference of the National Council on Family Relations, Minneapolis, MN.

Solmeyer, A., Killoren, S. E., McHale, S. M., & Updegraff, K. A. (2011). Coparenting around siblings’ differential treatment in Mexican-origin families. Journal of Family Psychology, 25, 251 – 260. doi:10.1037/a0023201

Sibling Relationships 929

Steelman, L. C., Powell, B., Werum, R., & Carter, S. (2002). Reconsidering the effects of sibling configuration: Recent advances and challenges. Annual Review of Sociology, 28, 243 – 269. doi:10.1146/annurev.soc.28.111301.093304

Stocker, C. M., Burwell, R. A., & Briggs, M. L. (2002). Sibling conflict in middle childhood predicts children’s adjustment in early adoles- cence. Journal of Family Psychology, 16, 50 – 57. doi:10.1037/0893-3200.16.1.50

Stocker, C. M., & Youngblade, L. (1999). Mar- ital conflict and parental hostility: Links with children’s sibling and peer relationships. Jour- nal of Family Psychology, 13, 598 – 609. doi:10.1037/0893-3200.13.4.598

Stoneman, Z. (2001). Supporting positive sibling rela- tionships during childhood. Mental Retardation and Developmental Disabilities Research Reviews, 7, 134 – 142. doi:10.1002/mrdd.1019

Stoneman, Z., & Brody, G. H. (1993). Sibling temperaments, conflict, warmth, and role asym- metry. Child Development, 64, 1786 – 1800. doi:10.1111/j.1467-8824.1993tb04213.x

Stoneman, Z., Brody, G. H., Churchill, S. L., & Winn, L. L. (1999). Effects of residential instability on Head Start children and their relationships with older siblings: Influences of child emotionality and conflict between family caregivers. Child Development, 70, 1246 – 1262. doi:10.1111/1467- 8624.00090

Stormshak, E., Bellanti, C., Bierman, K., & The Conduct Problems Prevention Research Group. (1996). The quality of sibling relationships and the development of social competence and behav- ioral control in aggressive children. Developmen- tal Psychology, 32, 79 – 89. doi:10.1037/0012- 1649.32.1.79

Strohschein, L., Gauthier, A. H., Campbell, R., & Kleparchuk, C. (2008). Parenting as a dynamic process: A test of the resource dilution hypothesis. Journal of Marriage and Family, 70, 670 – 683. doi:10.1111/j.1741-3737.2008.00513.x

Sulloway, F. J. (1996). Born to rebel: Birth order, family dynamics, and creative lives. New York: Pantheon Books.

Tucker, C. J., Updegraff, K. A., McHale, S. M., & Crouter, A. C. (1999). Older siblings as socializers of younger siblings’ empathy. Journal of Early Adolescence, 19, 176 – 198. doi:10.1177/ 0272431699019002003

Updegraff, K. A., McHale, S. M., & Crouter, A. C. (2002). Adolescents’ sibling relation- ships and friendships: Developmental patterns and relationship associations. Social Devel- opment, 11, 182 – 211. doi:10.1111/1467-9507. 00194

Updegraff, K. A., McHale, S. M., Killoren, S. E., & Rodriguez, S. A. (2010). Cultural variations in sibling relationships. In J. Caspi (Ed.), Sibling

development: Implications for mental health practitioners (pp. 83 – 105). New York: Springer.

Updegraff, K. A., McHale, S. M., Whiteman, S. D., Thayer, S. M., & Delgado, M. Y. (2005). Ado- lescent sibling relationships in Mexican American families: Exploring the role of familism. Jour- nal of Family Psychology, 19, 512 – 522. doi:10.1037/0893-3200.19.4.512

U.S. Census Bureau. (2011). Facts for features: Cinco de Mayo. Retrieved from http://www.census.gov/ newsroom/releases/pdf/cb11ff-09_cinco.pdf

Volling, B. L. (2012). Family transitions follow- ing the birth of a sibling: An empirical review of changes in the firstborn’s adjustment. Psy- chological Bulletin. Advance online publication. doi:10.1037/a0026921

Volling, B. L., & Elins, J. L. (1998). Family relationships and children’s emotional adjust- ment as correlates of maternal and paternal differential treatment: A replication with tod- dler and preschool siblings. Child Development, 69, 1640 – 1656. doi:10.1111/j.1467-8624.1998. tb06182.x

Weisner, T. S. (1989). Comparing sibling relation- ships across cultures. In P. G. Zukow (Ed.), Sib- ling interaction across cultures: Theoretical and methodological issues (pp. 11 – 22). New York: Springer-Verlag.

Whiteman, S. D., Bernard, J. M. B., & McHale, S. M. (2010). The nature and correlates of sibling influence in two-parent African American families. Journal of Marriage and Family, 72, 267 – 271. doi:10.1111/j.1741-3737.2010.00698.x

Whiteman, S. D., & Buchanan, C. M. (2002). Moth- ers’ and children’s expectations for adoles- cence: The impact of perceptions of an older sibling’s experience. Journal of Family Psy- chology, 16, 157 – 171. doi:10.1037/0893-3200. 16.2.157

Whiteman, S. D., McHale, S. M., & Crouter, A. C. (2003). What parents learn from experience: The first child as a first draft? Journal of Marriage and Family, 65, 608 – 621. doi:10.1111/j.1741- 3737.2003.00608.x

Whiteman, S. D., McHale, S. M., & Crouter, A. C. (2007). Competing processes of sibling influ- ence: Observational learning and sibling dei- dentification. Social Development, 16, 642 – 661. doi:10.1111/j.1467-9507.2007.00409x

Whiting, B. B., & Whiting, J. W. (1975). Children of six cultures: A psycho-cultural analysis. Cambridge, MA: Harvard University Press.

Widmer, E. D. (1997). Influence of older siblings on initiation of sexual intercourse. Journal of Marriage and the Family, 59, 928 – 938. doi:10. 2307/353793

Williams, P. D., Williams, A. R., Graff, C., Hanson, S., Stanton, A., Hafeman, C., & Sanders, S. (2003). A community-based intervention for

930 Journal of Marriage and Family

siblings and parents of children with chronic illness or disability: The ISEE study. Journal of Pediatrics, 143, 386 – 393. doi:10.1067/S0022- 3476(03)00391-3

Windle, M. (2000). Parental, sibling, and peer influences on adolescent substance use and alcohol problems. Applied Developmental Science, 4, 98 – 110. doi:10.1207/S1532480XADS0402_5

Youngblade, L. M., & Dunn, J. (1995). Individual differences in young children’s pretend play

with mother and sibling: Links to relationships and understanding of other people’s feelings and beliefs. Child Development, 66, 1472 – 1492. doi:10.2307/1131658

Zajonc, R. B., & Markus, G. B. (1975). Birth order and intellectual development. Psychological Review, 82, 74 – 88. doi:10.1037/h0076229