| Abstract: | ![]()
Summarizes all reliable published data about the nature and nurture of adopted children's IQs, and draws conclusions about the relative importance of heredity and environment on children's mental development. Any study that compares the central tendency of adopted children's IQs with a group mean of 100 IQ points for a normal population cannot be taken seriously until several methodological criteria have been met: (a) representative sampling, (b) no differential loss of Ss over time, (c) accurate, age-corrected information on biological and adoptive parents, (d) careful attention to early separation and placement of children, and (e) elimination of practice effects and regression to the mean artifacts. Analysis of the resemblance between individual adopted children's IQ scores and their adoptive and biological parents' mental abilities shows that the adoptive parents' home environment has only a modest effect on their adopted children's intellectual growth, while heredity and environment of the biological parents have a strong effect on their own children's intellectual growth. At present there is disagreement about the precise values of genetic and environmental effects on IQ, and several assumptions must be made before accurate statistics can be derived. But, the available data strongly suggest that under existing circumstances, heredity is much more important than environment in producing individual differences in IQ. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
