What is the proper interpretation of the Minnesota Transracial Adoption Study?

The Minnesota Transracial Adoption Study was a long project dedicated to directly measuring the influence of shared environment on the racial gaps in intelligence. The original paper about it came out in 1976 and the authors hypothesized that socialization in favorable environments would significantly reduce the racial gap in IQ (Scarr and Weinberg, 1976). At that point, the data did suggest an environmentalist hypothesis regarding race differences, however it was revisited by the authors in 1992, an event which caused much more controversy regarding the results. While the authors still supported an environmentalist position (Weinberg et al., 1992), their data brought a number of replies. In this post, I am going to summarize the main arguments used by the authors and review the replies as well as the authors’ responses to those replies.

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