Provides a comprehensive contemporary summary of the world literature on IQ correlations between relatives. A profile of average correlations consistent with a polygenic mode of inheritence is revealed from a summary of 111 studies, although a marked degree of heterogeneity of the correlations within familial groupings is also found. (CS)

Estimates the extent to which heredity influences perceptions of childhood family environment in a sample of 58 monozygotic and 46 dizygotic pairs of adult twins who were reared apart. The data confirm the importance of genetic factors in some, but not all, measures of family environment. Environmental influences were more important than genetic…

Described is an ongoing study of monozygotic and dizygotic twins, separated in infancy and reared apart. Discussed are the procedures and results of this study with interpretations of the results. The effects of parenting, education, and other interventions are considered. (CW)