Short Paper: Aggression in Childhood

O R I G I N A L P A P E R

Parental Influences on the Prevalence and Development of Child Aggressiveness

Klaus Wahl • Cornelia Metzner

Published online: 13 April 2011

� Springer Science+Business Media, LLC 2011

Abstract The development of aggressiveness between 5

and 17 years and some parental influences on this devel-

opment were analyzed using data from Germany. Interna-

tional studies have shown a ‘‘camel humps’’ curve, i.e., a

peak of aggression of children (primarily boys) between 2

and 4 years and a second peak of antisocial or aggressive

behavior of boys between 15 and 20 years, but small

groups of children and adolescents were persistently

aggressive. A representative longitudinal study (2,190

children and their parents) and an additional study (1,372

children and adolescents) were conducted in Germany. The

hypotheses of this article are that in the data can be found

(a) an U-shaped course of aggressiveness for boys and

girls, but on different levels, (b) a minority of persistently

aggressive children and youth, (c) influences of parental

temperaments, behavioral tendencies, parenting styles and

the family status on the children’s aggressiveness. The

results replicate roughly the ‘‘valley’’ of the U-shaped

course of aggressiveness. Small groups of chronically

aggressive children were found as well. Influences of

parental temperaments and corresponding behavioral ten-

dencies (internalizing and externalizing behavior), parent-

ing styles (child-centered communication, use of violence)

and the social status of the families on child aggressiveness

confirmed the hypotheses. These processes were moderated

by gender effects between mothers, fathers, daughters, and

sons. In regard to the group of persistently aggressive

young people prevention of aggression should start early in

childhood and over the long term. Parent education should

consider more the individual personalities of the parents,

not only parenting styles.

Keywords Aggression � Children � Adolescents � Parents � Longitudinal study � Germany

Introduction

During the last decades many societies were alarmed about

the increasing violence of adolescents (Bundeskriminalamt

2009; Krug et al. 2002). For a long time, research on the

causes of aggression and aggressiveness (as the disposition

for aggressive behavior) concentrated on adolescents

because their acts of violence are particularly visible to the

public (e.g., Stattin and Magnusson 1989). But it became

obvious that aggressiveness and certain forms of aggres-

sion arise earlier in life. There is some continuity of general

aggressiveness from childhood to adulthood; studies

determined that most adolescents and adults who commit

acts of violence were already aggressive or socially con-

spicuous as children (Alink et al. 2006; Huesmann et al.

2009; Kokko et al. 2009; Loeber et al. 2005; Tremblay

2000, 2007; Wahl 2002, 2003; Wahl et al. 2001). This is an

important insight for the early prevention of aggression and

for the role of parents in prevention programs.

However, the attempt to summarize research results on

the development of aggression starting in childhood is

confronted with a series of problems. For example, there is

no unified definition of aggression: It is sometimes regar-

ded as deliberate bodily harm done to another; but some-

times the criterion of intention is not included, especially

where children are concerned. Some studies use aggression

K. Wahl (&) Psychosocial Analyses and Prevention - Information System

(PAPIS), Höllriegelskreuther Str. 1, 81379 München, Germany

e-mail: [email protected]

C. Metzner

Fasanenhof Clinic, München, Germany

123

J Child Fam Stud (2012) 21:344–355

DOI 10.1007/s10826-011-9484-x

as a component of externalizing behavior or delinquency.

In this article aggression is regarded as an ensemble of

mechanisms formed during the course of evolution in order

to assert oneself, relatives or friends against others, to gain

or to defend resources (ultimate causes) by harmful dam-

aging means (for example, hitting others). These mecha-

nisms are often motivated by emotions like fear,

frustration, anger, feelings of stress, dominance or pleasure

(proximate causes). Aggression can be considered patho-

logical when it is exaggerated, persistent or expressed out

of context (Nelson and Trainor 2007; Wahl 2009). The

term aggressiveness is used for the individual disposition

for aggression (for example, expressed in a child’s desire to

start fights with others).

The methods of research into aggression are also

diverse, which has effects on the results: Aggressive

behavior is determined by self-reports from children, by

reports from parents, teachers, police, or the researchers

themselves. There are retrospective and prospective stud-

ies. Some studies only consider one gender, which is

usually boys because bodily aggression is more widespread

among them while girls tend more to indirect or ‘‘relational

aggression’’ (Foster and Hagan 2003), according to the

meta-analysis of 148 studies by Card et al. (2008).

In the last years there was more research on aggression

in young children. In a Dutch longitudinal study, parents

described a peak in the prevalence of physically aggressive

behavior (77%) among their two-year-olds (Alink et al.

2006). Based on international longitudinal studies

(including Nagin and Tremblay 1999), Tremblay (2007)

concludes that a peak of aggressive behavior is reached

between the end of the second and the end of the fourth

year. With regard to the persistently highly aggressive

children in the studies conducted by Tremblay, there was

no group of boys in which physical aggression first started

after the age of six and was maintained thereafter. The

National Longitudinal Survey of Children and Youth

(NLSCY) produced current results for 12,292 Canadian

children between the ages of 5 and 11 years. While 3.7% of

the boys remained frequently physically aggressive

throughout this age range, this number dropped from 2.3 to

0.5% for girls (Lee et al. 2007). In a representative sample

of the German Child and Adolescent Health Survey with

2,863 families with children between the ages of 7 and

17 years, 6–7% of these children and adolescents were

aggressive (Ravens-Sieberer et al. 2007).

A comparative analysis of six longitudinal studies in

New Zealand, the United States and Canada, which began

with several thousand participants at birth and continued

until adolescence, also explored the connection between

early physical aggression in childhood and later acts of

physical violence in adolescence. Depending on the sample

between 4 and 10% of the boys showed a continuity of

physical aggression. The boys who were already chroni-

cally aggressive in elementary school age had an increased

risk of higher levels of violent activity and other forms of

offenses later during their adolescence between the ages of

13 and 18. Among the girls, the chronically aggressive

groups fluctuated between 0 and 10% in the various studies

and there were no clear predictors of later behavior in

measured degrees of aggressive behavior in childhood.

These studies also concluded that chronically aggressive

children already display a high level of disruptive behavior

by the time they enter kindergarten (Broidy et al. 2003).

Moffitt (1993) identified two developmental paths in

male children and adolescents displaying antisocial

behavior including aggressive tendencies, to which the

greater majority could be classified, based on an analysis of

numerous studies: About two-thirds of the boys only epi-

sodically displayed conspicuous antisocial behavior during

adolescence (adolescence-limited). A small group of

approximately 5% of the boys already displayed such

behavior in the preschool stage of childhood and perma-

nently maintained it throughout adolescence (life-course

persistent).

In summarizing the insights of all these longitudinal

studies on the development of aggression and antisocial

behavior during childhood, there seems to be a first peak of

the prevalence of these behaviors around the third year,

particularly for boys. A second peak for the majority can be

found during mid to late adolescence—those who are

episodically conspicuous. Taken together in an ideal type,

the result is a ‘‘camel humps’’ curve of the prevalence of

(episodic) aggression in childhood and adolescence. Of

special interest is a small group of boys (and a very small

one of girls) at the base of this curve with considerable

antisocial behavior and particularly high levels of chronic

aggression during childhood and adolescence. In a first

step, this article examines whether the prevalence and the

development of child aggressiveness according to new data

from Germany corresponds to these international findings.

There is a wealth of biological, psychological and

sociological findings concerning the causes of aggression

and aggressiveness (summaries by Heitmeyer and Hagan

2003; Tremblay et al. 2005; Wahl 2009). Researchers

explain the early onset of aggressive behavior of children

by biological factors, learning processes and frustration

leading to aggressive reactions as early as in the first year.

Moreover, with an increasing sense of autonomy, children

come up against parental limits that could trigger aggres-

sion. Later, the level of children’s aggression decreases

because their moral development is so effective that they

display more socially acceptable behavior (Alink et al.

2006), they are better able to tolerate waiting for a reward

and to use language, rather than hitting, as a means of

convincing others beginning at this age (Tremblay 2007).

J Child Fam Stud (2012) 21:344–355 345

123

Parents can influence the aggressiveness of their chil-

dren in different ways, by their genes inducing precondi-

tions for aggressiveness (Pérusse and Gendreau 2005), by

the mothers’ behavior during pregnancy (e.g., smoking)

(Huijbregts et al. 2007), by the parenting style (Georgiou

2008), by the emotional family climate as a possible trigger

of children’s aggressiveness (Lau et al. 2006) and by the

socioeconomic and cultural environment (facilitated by

income, education, etc.) which they offer to the children

(Barker et al. 2008). In this article we are especially

interested in the parents’ role in the intergenerational

transmission of problem behavior like child aggressiveness

by some aspects of their general behavior (Meurs et al.

2009): (1) The parents’ temperaments expressed in corre-

sponding behavior tendencies (externalizing and internal-

izing behavior), (2) their parenting styles (child-centered

communication, control, violence; the emotional family

climate as result of parental behavior) and (3) the self-

images of the mothers and fathers. Children can react to all

these parental behaviors and expressions by insecure or

disorganized attachment, epigenetic reactions (e.g.,

increased sensitivity to environmental influences), identi-

fication, imitation, opposition and emotional reactions such

as fear, insecurity, frustration, anger, a sense of power-

lessness, low self-esteem, etc. which can promote aggres-

siveness (McNamara et al. 2010; Meyer-Lindenberg et al.

2006; Wahl 2002; Zoccolillo et al. 2005).

An interesting question is the mediating role of par-

enting on the relation between parental attributes and the

children’s behaviors (van Aken et al. 2007). Foci of this

article are on these two factors which are also relevant

for prevention programs for parents trying to minimize

child aggression. Up to now many of the prevention

programs are aiming at the socioeconomic situation of

the parents and the parenting styles (Brotman et al. 2008;

Tremblay 2008). This is not enough. The parents’ tem-

perament with corresponding behavioral tendencies (e.g.,

externalizing behavior) and affiliated attributes (e.g., self-

images of mothers and fathers) may interfere with

learning a modified parenting style, e.g., a mother’s

disposition to externalizing behavior makes it difficult for

her to raise her children without violence. We argue here

that prevention programs should consider that such fac-

tors play important roles for the development of child

aggressiveness.

The gender constellation between mothers, fathers,

daughters, and sons may also play a role, as shown by

Casas et al. (2006): A permissive style on the part of

mothers was associated with a higher degree of physical

aggressiveness in girls. In comparison, an authoritative (not

authoritarian) style was coupled with less aggressiveness in

girls. Boys and girls were more aggressive when the

mothers employed a psychologically controlling style of

parenting. When the fathers behaved like this, the girls

were more aggressive but not the boys.

Against this background, in a secondary analysis of the

data of a representative longitudinal study and an addi-

tional study on the situation of parents and children in

Germany we try to attain the following goals.

The first goal is an analysis of the prevalence and

development of child aggressiveness: Do these data confirm

international findings of decreasing prevalence of aggres-

siveness in boys and girls (on different levels) between 5

and 11 years, paralleled by a minority of chronically

aggressive children as a risk group for later criminal vio-

lence? Does an additional study confirm international

findings of an U-shaped curve between 5 and 17 years

corresponding with the valley of the ‘‘camel humps’’ curve?

The second goal of the article is an analysis of some

influences of parents on the aggressiveness of the children:

How strong are the relative effects of (1) some aspects of

the temperaments, behavioral tendencies and affiliated

attributes of the mothers and fathers, (2) the parenting

styles, and (3) the socioeconomic situation of the families

on the aggressiveness of their boys and girls? Regarding

the second goal, we want to test the hypothesis that the

mothers’ and fathers’ externalizing and internalizing

behaviors, their self-images and the family climate have

comparable strong effects on the development of aggres-

siveness in children as does the parenting style and the

socioeconomic situation of the parents. This would have

consequences for the starting points and foci for aggression

prevention, e.g., in parent education.

Methods

Participants

The following calculations use the data of the three survey

waves of the DJI Children’s Panel Study, a longitudinal

study of the German Youth Institute (Deutsches Jugend-

institut, DJI). It is based on a random sample of children

between 5 and 11 years (boys and girls with their parents)

from the registers of residents which is representative for

Germany (persons with migration backgrounds were

included if they had sufficient knowledge of German for

interviews and questionnaires). The first wave of surveys

was in 2002 with 2,190 families that had children in two

age cohorts (the younger with 5- to 6-year-olds; the older

cohort had 8- to 9-year-olds). Children and mothers were

surveyed at home through standardized interviews and the

fathers by questionnaires. For the 5- to 8-year-olds, for

methodological reasons (length and comprehensibility of

the interview) instead of the children the mothers were

consulted regarding the questions on behalf of the children.

346 J Child Fam Stud (2012) 21:344–355

123

The second wave of survey was in 2004 and the third in

2005. See Table 1 for the design of the DJI Children’s

Panel Study.

Besides the data from the DJI Children’s Panel, which

only extends to the age of about 11–12 years, data is also

available from an additional representative study by the

German Youth Institute starting in 2007 in which children

and adolescents in Germany between 13 and 17 years of

age were surveyed (N = 1,372). In both studies the chil-

dren and adolescents responded to the statement, ‘‘I like to

fight’’, on a four-tiered scale ranging from agreement to

disagreement.

Instruments

The Children’s Panel Study was planned by scientists from

the German Youth Institute as well as from German and

Austrian universities. The broad variety of their research

interests on the one hand and the limited duration of the

interviews on the other hand resulted in compromises like

shortened lists of items in some questions and tests. This

restricts the possible analyses in this article.

One of the main instruments of the DJI Children’s Panel

was a scale for the temperament and behavior of the

children. The 30 items came in parts from the Child

Behavior Checklist (CBCL) (Achenbach 1991), the Tem-

perament Scale (Windle and Lerner 1986) or its shortened

version (Schwarz and Rinker 1998), and a Leipzig Longi-

tudinal Study (Zentralinstitut für Jugendforschung 1988).

Based on a factor analysis three indices were formed from

this scale to determine the aggressiveness of the children

(from the perspective of the children, mothers, and fathers)

in the three survey waves by the average of the answer

values for the items ‘‘likes to fight’’, ‘‘enjoys making others

angry’’, ‘‘often starts arguments with others’’ on a scale of

1 (completely incorrect) to 4 (completely correct). For the

mothers’ perspective on the children’s aggressiveness the

internal consistency (Cronbach’s a) for the three waves was .67, .69, and .70 (fathers’ perspective: .71, .71, .74; chil-

dren’s perspective: .51, .50, .53). In the following text the

degrees of child aggressiveness resulting from combina-

tions of the three perspectives or for means over the three

survey waves are described as aggressive (with a value of

3.00–4.00 on the scale), slightly aggressive (2.01–2.99) and

not aggressive (1.00–2.00).

For gathering statistics about some aspects of the tem-

perament and behavior of the parents, the mothers and

fathers were asked to respond to 11 items on a newly

developed four-level response scale covering three

dimensions (according to a factor analysis): Four items

such as ‘‘sometimes I am sad’’, ‘‘I sometimes feel unsure of

myself’’ (mothers’ perspective in the first wave: a = .71; fathers’ perspective: .75) attributed to a factor which

described a depressive mood and internalizing behavior.

Other factors were impulsivity/rage (predisposing to

externalizing behavior) with two items: ‘‘I often act before

thinking things over’’ and ‘‘I am often angry at others’’ (in

the case of two items the correlation is calculated instead of

a: Mothers’ perspective r = .34** and fathers’ perspective r = .33**; **P B .01) and a positive self-image: Five

items such as ‘‘I am usually in a good mood’’, ‘‘I am proud

of things that I have accomplished’’ (a = .63 and .61). The second wave of the DJI Children’s Panel Study also

investigated the parenting styles in two dimensions:

attention and control. Using a scale in accordance with

Simons et al. (1992), the parents provided information

about the mothers’ and fathers’ communication with their

children with regard to how much attention they pay to the

children’s needs and desires. Child-centered communica-

tion was measured by six items such as ‘‘speaking with the

Table 1 Design of the DJI children’s panel study. The gray

boxes represent the two age

cohorts

DJI Children’s Panel Study Child’s age

First wave n = 2190

Second wave n = 1493

Third wave n = 1293

21-11 620 mothers 351 fathers 620 children

9-10 722 mothers 484 fathers 722 children

8-9 1042 mothers 658 fathers 1042 children

673 mothers 379 fathers 673 children

6-7 771 mothers 503 fathers child mother (proxy)

5-6 1148 mothers 678 fathers child mother (proxy)

J Child Fam Stud (2012) 21:344–355 347

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child about his/her experiences’’ and ‘‘asking the child’s

opinion in matters that concern him/her’’ (mothers’ per-

spective a = .70, fathers’ perspective .75). In addition, parents informed about the extent to which they exercise

strict or mild control in parenting using a scale of Schwarz

et al. (1997) with five items such as ‘‘I don’t think that a

child should defy adults’’ and ‘‘I believe in punishment if

the child acts against my will’’ (a = .70 and .74). The use of violence in child-raising was asked by means of an

abridged version of the Conflict Tactics Scales (CTS)

(Straus 2007) with three items to report on their own

behavior: ‘‘Spanking or shaking the child’’, ‘‘slapping the

face’’, and ‘‘hitting’’ (a = .58 and .63). The emotional climate in the family was determined from

the combined perspectives of the parents and the children

through a scale of five items (according to Zinnecker and

Silbereisen 1996) that includes questions such as whether

there is often ‘‘friction within the family’’, whether it is

‘‘possible for family members to speak freely’’, and whether

‘‘each member goes his/her own way’’ (a = .70). The family income, the educational level of the mothers

and fathers and a migrant background of the child were

used as variables for the social status and the living con-

ditions of the families. The family income (resulting from

the information given by the fathers and the mothers) was

measured in accordance with the equivalence income

defined by the OECD, i.e., the income of the parents set off

against various weighting for adults, children up to and

older than 14 years (cf. Alt and Quellenberg 2005, p. 289);

the educational level of the parents reached from ‘‘no

graduation’’ up to ‘‘high school graduation and higher’’; the

migrant background of the child was defined following the

German Federal Statistical Office as born as a foreigner in

Germany or immigrated to Germany or with at least one

parent who immigrated to Germany.

The data analysis (by SPSS) of the Children’s Panel Study

had two steps: First, descriptive statistics were performed to

assess the prevalence and development of child aggressive-

ness from the combined perspectives of the mothers, fathers,

and children. Second, we calculated correlations between

temperaments, behavioral tendencies and affiliated attri-

butes of the parents and the children’s aggressiveness.

Finally, we used these variables for a stepwise regression

analysis predicting children’s aggressiveness.

Results

Development of Physical Aggressiveness in Children

and Adolescents

The parents assessed the level of their children’s aggres-

siveness as significantly higher than the children

themselves. The children’s self-perspective showed a

stronger correlation with the perspective of the mothers

(rwave 1 = .47**, rwave 2 = .45**, and rwave 3 = .47**;

both here and below **P \ .01 and *P \ .05) than with the perspective of the fathers (rwave 1 = .38**, rwave 2 =

.42** and rwave 3 = .31**). While the parents’ assessments

of aggressiveness tended to decline with increasing age,

the self-perception of the children remained nearly

unchanged.

The most ratings of the children’s aggressiveness came

from the mothers because only this group rated the children

between 5 and 8 years and the mothers outnumbered the

fathers. So from the mothers’ perspective, 2.3% of the

children were persistently aggressive (i.e., with values of

3.00 or more in all three waves), 3.6% of the boys and

1.0% of the girls. Half of the children (49.6%) were never

aggressive (38.3% of the boys and 60.5% of the girls).

21.4% were decreasingly aggressive; 9.8% were increas-

ingly aggressive.

Both age cohorts of children that were assessed in the

three survey waves allow age-related differentiated state-

ments about the development of the prevalence and the

degrees of child aggressiveness from the perspectives of

the mothers (Table 2).

The portions of aggressive children between the ages

of 5 and 11 decreased for both genders. Among the

aggressive boys, this prevalence decreased from 19.8%

among those with 5 years to 9.8% among those with

11 years, i.e., by a half. Among the aggressive girls, the

portion dropped from 11.2 to 3.8%, i.e., by almost two-

thirds. As regards the means of child aggressiveness, it

decreased in this time significantly from 1.71 to 1.37 for

the boys and from 1.45 to 1.18 for the girls (P \ .001). The fathers and the children themselves also described

the boys as aggressive with significantly greater fre-

quency than the girls.

The combination of results from the Children’s Panel

(starting at age 8, when the children themselves were

interviewed) and the additional study with children and

adolescents from 13 to 17 years reveal an age-related dis-

tribution for the item ‘‘I like to fight’’ as a measure for

aggressiveness for both genders from 8 to 17 years of age

(Wahl 2010) as shown in Table 3.

A synopsis of the data of the two studies shows that

among boys and girls there was a first peak of the desire to

fight at the age of 9 years. In the following years this

indicator of aggressiveness decreased up to the age of 13.

Among boys this was followed by an increase up to the age

of 16, and then a decrease again up to the age of 17.

Among girls there was a fluctuating distribution between

the ages of 13 and 17. All in all, there is a roughly

U-shaped development in the distribution of aggressive-

ness, particularly among boys.

348 J Child Fam Stud (2012) 21:344–355

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Factors that Promote Aggressiveness in Children

The hypothesis of this article is that specific aspects of

parental attributes (externalizing and internalizing behav-

ior, self-image) have comparable strong effects on the

development of child aggressiveness as parenting styles

and the social status of the families. As a preparatory step

to test this hypothesis, correlations between these variables

and children’s aggressiveness are presented in Table 4.

All variables apart from the parents’ self-images and

educational levels showed significant correlations with the

children’s aggressiveness, but gender modified these cor-

relations. As Table 4 displays as well, the gender of parents

and children had an influence on the strength of the cor-

relations between parental behavioral tendencies and

attributes, parenting styles and child aggressiveness.

Comparatively strong correlations were between the

mothers’ and fathers’ low level of child-centered

communication as well as their use of violence in parenting

and the children’s aggressiveness. Higher paternal exter-

nalizing behavior was related to more aggression in girls,

higher paternal internalizing behavior was related to more

aggression in boys. A low family income was correlated

with higher aggressiveness of girls.

A stepwise regression analysis provided more informa-

tion about the effects of the groups of factors in mothers’

and fathers’ attributes and parenting styles compared with

other variables (Table 5).

The steps of this analysis introduced consecutively the

children’s gender, mothers’ and fathers’ parenting styles,

the family climate, mothers’ and fathers’ behavioral ten-

dencies and the social status of the family. After the last

step (step 7) the explained variance of child aggressive-

ness was R2 = .27. Step 1 (child’s gender) had a com-

paratively strong significant effect. Step 2 (mother’s

parenting style) and step 5 (mother’s behavioral

Table 2 Prevalence and degree of child aggressiveness according to age and gender (mothers’ perspective; percentages, means, standard deviations, and confidence intervals)

Age (years)

5 6 7 8 9 10 11

Prevalence of aggressiveness (%)

Boys

Aggressive 19.8 17.6 20.9 13.2 14.9 8.1 9.8

Slightly aggressive 31.1 33.8 28.5 24.5 14.3 24.2 17.5

Not aggressive 49.1 48.6 50.6 62.4 70.8 67.7 72.7

Girls

Aggressive 11.2 10.9 9.0 6.7 4.7 5.0 3.8

Slightly aggressive 22.2 19.4 15.4 11.8 17.0 14.4 10.1

Not aggressive 66.5 69.7 75.6 81.5 78.4 80.7 86.1

Degree of aggressiveness (M)

Boys

M 1.71 1.69 1.70 1.51 1.51 1.40 1.37

SD .78 .75 .79 .72 .71 .64 .66

95% CI 1.64 1.57 1.60 1.44 1.36 1.31 1.30

1.78 1.81 1.80 1.58 1.66 1.49 1.45

n 485 148 239 433 88 198 285

Girls

M 1.45 1.41 1.33 1.25 1.25 1.24 1.18

SD .69 .68 .64 .57 .52 .54 .47

95% CI 1.38 1.31 1.25 1.20 1.13 1.16 1.12

1.51 1.51 1.42 1.31 1.36 1.32 1.23

n 454 175 201 416 77 181 288

N 939 323 440 849 165 379 573

M mean; SD standard deviation; CI confidence interval. Difference of means between boys and girls: ** P \ .01. Sometimes children of the same age were included in more than one survey wave. To simplify the table for these cases only the boys and girls of the wave with the greatest

number of children of this age were considered. There were only 36 children in the age group of 12-year-olds, therefore no percentages and

means were calculated for this group

J Child Fam Stud (2012) 21:344–355 349

123

tendencies) led to the highest increase of the explained

variance (DR2). The emotional family climate (step 4) had only very small effects. The father’s behavioral tendencies

(step 6) and the social status of the family (step 7) as well

brought small effects as shown by the variance of chil-

dren’s aggressiveness explained by these groups of fac-

tors. Looking at the individual standardized regression

coefficients, the results of the correlation analysis were

partially echoed by the significant weights of the mothers

with low child centered communication, externalizing

fathers and low family income. All in all, the effect of the

fathers’ variables was weaker than the effect of the

mothers’ variables. Separate stepwise regression analyses

for boys and girls resulted in additional effects: In the case

of the boys the mother’s positive self-image and in the

case of girls the migrant background had significant

impacts.

Discussion

Due to the various definitions and methods used in the

international studies on child aggression and aggressive-

ness summarized at the beginning, as well as in the DJI

Children’s Panel Study and the additional study, the find-

ings on the extent of such behavioral tendencies cannot be

precisely compared. However, this is possible for the

structure (e. g., the stronger distribution among boys than

girls) and the trajectories through the age levels. Our data

showed a decreasing prevalence of aggressiveness between

5 and 11 years in Germany which is consistent with

international longitudinal studies. In combination with the

data of an additional study with adolescents up to 17 years

the prevalence of aggressiveness (as the desire to fight)

followed roughly an U-shaped curve corresponding to the

‘‘valley’’ of the ‘‘camel humps’’ curve, but somewhat

Table 3 Agreement of children and adolescents with the statement ‘‘I like to fight’’ by age and gender (children’s perspective; percentages, means, standard deviations, and confidence intervals)

Children’s panel study Additional study

Age (years) Age (years)

8 9 10 11 13 14 15 16 17

‘‘I like to fight’’ (%)

Boys

Strongly agree 16.7 20.5 10.7 8.1 0.9 3.8 4.9 2.5 1.9

Agree 15.5 23.9 14.2 13.3 13.9 7.1 11 15.9 12.5

Disagree 20.6 20.5 28.9 37.2 30.6 45.5 39.9 44.6 40.4

Strongly disagree 47.2 35.2 46.2 41.4 54.6 43.6 44.2 36.9 45.2

Girls

Strongly agree 7.6 10.4 6.7 8.4 0 3.6 3.9 1.3 3.3

Agree 8.1 7.8 8.3 5.6 4.3 5.1 5.5 9.3 9.8

Disagree 15.9 23.4 21.1 17.4 39.1 42 27.1 37.1 28.7

Strongly disagree 68.5 58.4 63.9 68.6 56.5 49.3 63.5 52.3 58.2

Degree of aggressiveness (M)

Boys

M 2.02 2.30 1.89 1.88 1.61 1.71 1.77 1.84 1.71

SD 1.14 1.16 1.01 .93 .76 .76 .84 .78 .76

95% CI 1.91 2.05 1.75 1.77 1.47 1.59 1.64 1.72 1.56

2.12 2.54 2.04 1.99 1.76 1.83 1.90 1.96 1.86

n 432 88 197 285 108 156 163 157 104

Girls

M 1.55 1.70 1.58 1.54 1.48 1.63 1.50 1.60 1.58

SD .93 1.00 .90 .93 .58 .75 .77 .71 .80

95% CI 1.46 1.47 1.45 1.43 1.36 1.50 1.38 1.48 1.44

1.93 1.71 1.64 1.64 1.76 1.61 1.71 1.73 1.64

n 409 77 180 287 92 138 181 151 122

N 841 165 377 572 200 294 344 308 226

DJI Children’s Panel Study and Additional Study. M mean; SD standard deviation; CI confidence interval. Sometimes children and adolescents of the same age were interviewed in more than one survey wave. To simplify the table for these cases only the boys and girls of the wave with the

greatest number of children of this age were considered

350 J Child Fam Stud (2012) 21:344–355

123

phase-delayed in comparison to other studies: Our data

suggests (at least for the indicator of ‘‘desire to fight’’) a

later first peak and a somewhat later low point in the

development of aggressiveness. Also, the existence of a

small group of chronically aggressive children (primarily

boys) in the Children’s Panel conforms to findings of

international studies (Alink et al. 2006; Lay et al. 2005;

Moffitt 1993; Moffitt et al. 1996; Tremblay 2007).

In addition, our data explored effects of some aspects of

the parental temperaments, behavioral tendencies, parent-

ing styles, self-images, and the social status of the families

on child aggressiveness that confirm and specify our

hypothesis: There were significant connections between

some aspects of the parents’ temperament and behavior

(particularly internalizing and externalizing behavior) and

child aggressiveness. Among the parenting styles, a weak

child-centered communication and the use of violence in

parenting were effective. The family climate had only

minor effects. The family income and to a smaller degree a

migrant background and the educational level of the

mothers influenced the children’s aggressiveness. Some

effects of the parents’ attributes and parenting styles

depended on the gender of the parents and children (e.g.,

fathers’ violence in child-rearing was more correlated with

aggressiveness of boys than of girls). All in all, the moth-

ers’ impact on child aggressiveness was higher than the

fathers’ impact. Compared to parenting styles, some

aspects of the parents’ temperament and behavioral ten-

dencies had a remarkable impact on the aggressiveness of

their children.

In sum, most parts of the hypotheses of this article were

confirmed: Within the limits of the measured variables,

aspects of the parental temperament or behavioral ten-

dencies had at least as strong effects on the development of

aggressiveness in children as the parenting styles and the

social status of the parents. What are possible explanations

for that? Temperament and corresponding behavioral ten-

dencies of parents and children are strongly influenced by

shared genes favoring similar personalities and behaviors.

In contrast, the effects of parenting styles are contingent

learning processes in which children can react to their

parents by all degrees of adaptation and resistance.

However, biological, learning and environmental factors

work together in influencing the aggressiveness of children.

The past years have seen increasing interdisciplinary

research on revealing this complicated interplay of bio-

logical, psychological and environmental influences on

aggression: Environmental factors can influence gene

expression (epigenetics) or interfere with brain maturation.

Genetic factors can affect brain areas to the extent that

children become particularly sensitive with regard to

environmental experiences (Meyer-Lindenberg et al.

2006). Hyperactive children provoke hostile parenting

behavior, which in turn makes the children aggressive

(Thomas and Chess 1977). Regarding influences on chil-

dren’s aggressiveness, Tremblay and Szyf hypothesize that

environmental effects are transmitted intergenerationally,

most clearly from mothers to daughters; e.g., smoking,

stress and depression during pregnancy have epigenetic

effects on the daughter’s brain development. The daughter

probably will have a similar lifestyle during her own

pregnancies, and so on. In this way, mother to daughter

epigenetic transmission of behavior problems could be the

hidden mechanism of intergenerational transmission of

male chronic aggression (Tremblay and Szyf 2010). Fol-

lowing this line of argument and the results of the DJI

Children’s Panel, a wide spectrum of behavior patterns of

mothers and fathers should be regarded as possible factors

for the children’s aggressiveness, not only parenting styles

as a focus of many contemporary parent education

programs.

Our data show a connection between the externalizing

behavior of parents and the aggressiveness of their chil-

dren. This can be done by different processes (genes,

imitation, frustration) (Leve et al. 2010). The effects of

high degrees of internalizing behavior of parents on the

children’s aggressiveness (as in the data of the Children’s

Panel) are complicated as well. Studies of Loeber et al.

(1998) and Garland (2007) suggest that anxiety, depression

Table 4 Correlations of variables (survey waves 1 and 2) with children’s aggressiveness (survey wave 3)

Variables Survey

wave

Total

r Boys

r Girls

r

Child’s gender a

1 -.24**

Child-centered mother 2 -.19** -.19** -.12*

Controlling mother 2 .12** .07 .13*

Violent mother 2 .22** .17** .19**

Child-centered father 2 -.17** -.16** -.16**

Controlling father 2 .11** .09 .04

Violent father 2 .20** .17** .11*

Good family climate 2 -.13** -.15 -.15

Externalizing mother 1 .13** .10 .11*

Internalizing mother 1 .15** .13* .13*

Mother’s positive self-image 1 .03 .05 .01

Externalizing father 1 .16** .14* .21**

Internalizing father 1 .14** .17** .09

Father’s positive self-image 1 -.04 -.07 .02

Mother’s educational level 1 .01 .05 -.02

Father’s educational level 1 .01 -.01 -.02

Family income 1 -.10* -.04 -.16**

Migrant background b

1 .06* .06 .04

n 292–726 149–365 143–361

Reference categories: a

boy, b

no migrant background. r Pearson’s correlation or Kendall’s tau b. ** P \ .01; * P \ .05

J Child Fam Stud (2012) 21:344–355 351

123

and related stress contribute to a parent’s problematic use

of parenting techniques which in turn leads to aggressive-

ness in children. However, more aspects of child-raising

behavior might be influenced by the internalizing behavior

of parents, e.g., inconsistencies of the parental behavior.

Another study with the data from the Children’s Panel

revealed that such inconsistencies lead to more external-

izing behavior of the children (Huber 2008).

In parenting, a low level of child-centered communi-

cation and the use of physical violence can activate

aggressiveness in the children, as shown by our data. Using

violence in child rearing, as manifested by a part of the

mothers and fathers in this study, may be connected with a

child’s aggressiveness by different mechanisms, e.g., imi-

tation, a frustration-aggression reaction or by a number of

shared genes of parents and children (Baker et al. 2007;

Brendgen et al. 2005; Hudziak et al. 2003; Miles and Carey

1997; van den Oord et al. 1994; Wahl 2009).

In addition, the research literature reports on various

effects of parental styles on child aggressiveness depending

on the gender constellation between mothers, fathers, girls,

and boys that is considered (e.g., Casas et al. 2006). This

can be confirmed by the data from the Children’s Panel

Study. The influences of maternal parenting differed from

those of paternal parenting and both parenting styles

depended on the child’s gender. We could hypothesize that

boys rather react disappointed, angrily and aggressively to

fathers’ internalizing behavior and girls react angrily and

aggressively to fathers’ externalizing behavior because it is

contrary to their role expectations. Future research should

offer more answers to open questions about such

differences.

Aspects of the social status like the educational level of

the parents, the family income and a migrant background

are part of the ‘‘usual suspects’’ in aggression research

(Wahl 2009, p. 153 ff) and they were found correlated with

Table 5 Stepwise regressions predicting children’s aggressiveness (b)

Variables Standardized regression coefficients (b)

Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7

Child’s gender a

-.28** -.22** -.21** -.22* -.19** -.21** -.19**

Mother’s parenting style

Child-centered mother -.18** -.14* -.13 -.10 -.08 -.07

Controlling mother .06 .06 .06 .07 .06 .06

Violent mother .11 .10 .09 .09 .10 .09

Father’s parenting style

Child-centered father -.10 -.07 -.07 -.07 -.03

Controlling father .01 .01 .04 .05 .05

Violent father .02 .02 .03 .02 .00

Family climate -.09 -.06 -.05 -.09

Mother’s behavioral tendencies

Externalizing mother .06 .07 .10

Internalizing mother .21** .20** .18**

Mother’s positive self-image .07 .08 .09

Father’s behavioral tendencies

Externalizing father .15* .13

Internalizing father .05 .04

Father’s positive self-image .02 .01

Social status

Mother’s education -.10

Father’s education .08

Family income -.14*

Migrant background b

.14

Constant 2.03 2.36 2.48 2.70 1.93 1.55 1.55

Standard error .42 .41 .41 .41 .40 .40 .39

R2 .08 .14 .15 .15 .20 .23 .27

DR2 .06** .01 .01 .05** .03 .04*

Reference categories: a

boy, b

no migrant background. N = 292, ** P \ .01; * P \ .05

352 J Child Fam Stud (2012) 21:344–355

123

child aggressiveness in our data as well. These variables

imply knowledge deficits or could lead to negative patterns

of parenting according to the frustration-aggression theory.

The findings of this secondary analysis of the data from

the DJI Children’s Panel are subject to some limitations

caused by the design, the sample, and the methods of this

study which was a compromise of interests of a heteroge-

neous group of scientists from different institutes and

scarce resources. The target person of the study refused to

participate in approximately one quarter of the gross ran-

dom sample. Due to these refusals and the exclusion of

migrants with insufficient knowledge of German (there was

an additional study for migrants who did not speak German

at all) persons with certain difficulties in life might be

underrepresented. As usual in longitudinal studies the

decreasing number of participants from one survey wave to

the next might have led to a greater loss of persons with life

problems than others. Older children and mothers were

questioned by interviewers; the fathers filled out a ques-

tionnaire, this difference could imply some distortions in

the responses. Despite the interviewers’ efforts, they were

not always successful in questioning the children in

absence of the mothers and fathers.

Family socialization includes two-way processes, e.g.,

the effects between negative parenting and child aggression

are bidirectional (Vitaro et al. 2006). Such effects need

more research. Nevertheless, the study has determined that

some personal characteristics of the parents (e.g., inter-

nalizing and externalizing behavior) seem to have signifi-

cant influences on the degree of child aggressiveness. The

effects of these personal attributes seem to be as strong as

various aspects of the parenting style or the family income.

For a more systematic analysis of the relations between

parents’ temperament, their corresponding behavioral ten-

dencies and parenting styles further research is needed

because the Children’s Panel offered only a restricted set of

variables. The strengths of the DJI Children’s Panel are the

representative sample, the longitudinal design, and the

three-sided perspectives from the mothers, fathers, and

children.

Considering the children with high degrees of aggres-

siveness with only 5 years of age and continuing aggres-

siveness one consequence for the practice has become

clear: Since the development of aggression in future violent

criminals not only has a considerable genetic component

but can also be promoted by influences of the social

environment beginning during pregnancy, by epigenetic

processes starting early in life in the family, by parenting

styles etc., measures to prevent aggression and violence

should be initiated at a very early stage and over the long

term, and they have to consider the individual personalities

of parents, not only the parenting styles. This is an

important advice for parent education, too.

Acknowledgments The empirical research was supported by the German Youth Institute, Munich. The review of literature was facil-

itated by a fellowship from the Institute for Advanced Study, Del-

menhorst, awarded to Klaus Wahl. We thank the families who

participated in the studies and Christian Alt, Beatriz Barquero, and

Ulrich Pötter for comments on drafts of the text.

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