Research has shown that differences among ordinary people in intelligence and personality depend equally on individual genetic variability and on differences in the environments that siblings experience within the same family, not differences in the neighborhood, school, and community environments. As of yet, there are no adequate theories to…

Findings from a study reported in this paper indicate that the differences in family background that affect IQ are largely the result of genetic differences among parents, which affect the parents' own status attainment and which are passed on genetically to their offspring, whose status attainments are subsequently affected. (Author/EB)

Posits that an evolutionary perspective can unite the study of the typical development for and individual variation within a species and that environments within the normal range for a species are required for species-normal development. Individual differences in children reared in normal environments arise primarily from genetic variation and…