Nature or Nurture

Charles Darwin's cousin, Sir Francis Galton, examined his peers and saw that many of the most prominent people in society came from just a small number of different families.  Why is this observation insufficient evidence to conclude that intelligence is an inherited (nature) ability rather than a product of environmental influences (nurture)?  Discuss how intellectual ability is strongly influenced by culture.   Include a reference/URL to an article you found on the link between culture and intelligence.   Do you agree or disagree with this concept?  Have you encountered expectations about intelligence based on your ethnicity, socioeconomic status, or some other criteria?