RACIAL-GROUP DIFFERENCES IN IQ IN THE MINNESOTA TRANSRACIAL ADOPTION STUDY - A REPLY TO LEVIN AND LYNN

The etiology of racial differences in intelligence and achievement is one of the most heated areas of social science research. In this artic le, we respond to criticisms by Levin and Lynn of our 1992 follow-up s tudy of IQ and achievement in a sample of transracial adoptees and the ir families, in particular to their assertion that our results provide strong support for a genetic etiology underlying racial differences i n measured intelligence. In that follow-up, as well as in publications from the original study (Scarr & Weinberg, 1976, 1977), we argued for beneficial effects on transracial adoptees' IQs and achievements due to being raised in white, upper-middle-class homes. In this article, w e address a number of issues raised in Levin's and Lynn's critiques, i ncluding the magnitude of adoptee racial-group differences in IQ and a chievement, the inclusion of white and Asian/Indian adoptee groups in such analyses, the confounding of important early environmental influe nces with race differences, the confusion of within-group and between- group influences on IQ, the regional U.S. differences in African-Ameri can norms for IQ and achievement, the effects of renormed IQ tests on adoptee group differences, and the nature of the available evidence re garding a genetic hypothesis for racial differences in intelligence. W e argue that, contrary to Levin's and Lynn's assertions, results from the Minnesota Transracial Adoption Study provide little or no conclusi ve evidence for genetic influences underlying racial differences in in telligence and achievement.