Individual and Group Differences in Adoption Studies of IQ

摘要: In the last 5 years, Colorado and Texas adoption projects have replicated elaborated findings of classical studies this century: IQs adoptees are more strongly related to their biological parents than measurable characteristics adoptive environment. At same time, several from France demonstrated substantial IQ gains in children adopted impoverished middle-class homes. The apparent contradiction between these two is emblematic nature-nurture controversy. A common model for resolving paradox, two-realms hypothesis, conceptually inadequate encourages separate analysis individual group differences. Subsuming kinds a single shows that they less divergent seem highlights need further research into why some contradictions remain. Despite periodic declarations peace (Clarke, 1984b; Plomin, 1983; Scarr & Weinberg, 1980; Wachs, 1983) or victory (Feldman Lewontin, 1975; Urbach, 1974), debate has not been resolved. There many reasons its continuation, scientific ideological. Among most important persistently opposite conclusions varieties design. one (the individual-difference design), measure Positive statistical relationships IQsofbiological adopted-away indicative genetic effect; positive rearing environment children's demonstrate environmental influences. other (group-difference) design focuses on differences mean groups. Children unfortunate circumstances environmentally favorable homes evaluated see if improvement accompanied by an increase IQ. Beginning with classic Burks (1928) Leahy (1935), analyses usually shown stronger parents' measures thus supported genetically weighted conclusions. contrast, deprived environments stable often significant increments IQ, consistent explanation. Indeed, sometimes reported study. divergence individual- group-difference traditions now practically complete. Recent reviews