[aerovistae]

Did you read your own source?

> Currently, there is no non-circumstantial evidence that these differences in test scores have a genetic component,

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> Soon, other studies appeared, contesting these conclusions and arguing instead that the Army tests had not adequately controlled for the environmental factors such as socio-economic and educational inequality between African-Americans and Whites.

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> The majority of anthropologists today consider race to be a sociopolitical phenomenon rather than a biological one,[34] a view supported by considerable genetics research.

[poke111]

I didn't mean to imply that I knew the answer to your question. I meant that the IQ disparity is a statistical fact, but the cause is a hotly debated area of research without clear answers, and the Wikipedia page is a good primer on the various sides of the debate. The point is that in a study like this you may have to adjust for oversampling by race.