Magazine article The American Prospect

The Heredity-Environment Controversy

Magazine article The American Prospect

The Heredity-Environment Controversy

Article excerpt

When the U.S. Army launched America's first large-scale mental testing program in 1917, whites scored substantially higher than blacks. Biological determinists immediately cited these findings as evidence that whites had more innate ability than blacks, but cultural determinists quickly challenged this interpretation. Neither side had a convincing way of separating the effects of heredity from the effects of culture, so the debate was an empirical standoff.

After 1945, the horrors of the Holocaust made all genetic explanations of human differences politically suspect. Once the U.S. Supreme Court declared de jure racial segregation unconstitutional in 1954, genetic explanations of racial differences became doubly suspect, because they were identified with southern resistance to desegregation. As a result, environmental explanations remained dominant throughout the 1960s. Then in 1969 Arthur Jensen published an article in the Harvard Educational Review arguing that educational programs for disadvantaged children initiated as part of the War on Poverty had failed, and that the blackwhite test score gap probably had a substantial genetic component. Jensen's argument went roughly as follows: (1) Most of the variation in white IQ scores is genetic; (2) no one has advanced a plausible environmental explanation for the black-white gap; therefore, (3) it is more reasonable to assume that part of the black-white gap is genetic than to assume it is entirely environmental.

Jensen's article created such a furor that psychologists once again began looking for evidence that bore directly on the question of whether racial differences in test performance were partly innate, (Richard Nisbett reviews these studies in The Black-White Test Score Gap.)

Two small studies have tried to compare genetically similar children raised in black and white families. Elsie Moore found that black children adopted by white parents had IQ scores 13.5 points higher than black children adopted by black parents. Lee Willerman and his colleagues compared children with a black mother and a white father to children with a white mother and a black father. The cleanest comparison is for mixed-race children who lived only with their mother. Mixed-race children who lived with a white mother scored 11 points higher than mixed-race children who lived with a black mother. Since the black-white IQ gap averaged about 15 points at the time these two studies were done, they imply that about four-fifths of that gap was traceable to family-related factors (including schools and neighborhoods).

A better-known study dealt with black and mixed-race children adopted by white parents in Minnesota. The mixed-race children were adopted earlier in life and had higher IQ scores than the children with two black parents. When the 29 black children were first tested, they scored at least ten points higher than the norm for black children, presumably because they had more favorable home environments than most black children. When these children were retested in their late teens or twenties, their IQ scores had dropped and were no longer very different from those of northern blacks raised in black families. The most obvious explanation for this drop is that the adoptees had moved out of their white adoptive parents' homes into less favorable environments. …

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