Academic journal article The Future of Children

Genetic Differences and School Readiness

Academic journal article The Future of Children

Genetic Differences and School Readiness

Article excerpt

The author considers whether differences in genetic endowment may account for racial and ethnic differences in school readiness. While acknowledging an important role for genes in explaining differences within races, he nevertheless argues that environment explains most of the gap between blacks and whites, leaving little role for genetics.

Based on a wide range of direct and indirect evidence, particularly work by Klaus Eyferth and James Flynn, the author concludes that the black-white gap is not substantially genetic in orgin. In studies in 1959 and 1961, Eyferth first pointed to the near-disappearance of the black-white gap among children of black and white servicemen raised by German mothers after World War II. In the author's view, Flynn's exhaustive 1980 analysis of Eyferth's work provides close to definitive evidence that the black disadvantage is not genetic to any important degree.

But even studies showing an important role for genes in explaining within-group differences, he says, do not rule out the possibility of improving the school performance of disadvantaged children through interventions aimed at improving their school readiness. Such interventions, he argues, should stand or fall on their own costs and benefits. And behavioral genetics offers some lessons in designing and evaluating interventions. Because normal differences in preschool resources or parenting practices in working- and middle-class families have only limited effects on school readiness, interventions can have large effects only if they significantly change the allocation of resources or the nature of parenting practices.

The effects of most interventions on cognitive ability resemble the effect of exercise on physical conditioning: they are profound but short-lived. But if interventions make even small permanent changes in behavior that support improved cognitive ability, they can set off multiplier processes, with improved ability leading to more stimulating environments and still further improvements in ability. The best interventions, argues the author, would saturate a social group and reinforce individual multiplier effects by social multipliers and feedback effects. The aim of preschool programs, for example, should be to get students to continue to seek out the cognitive stimulation the program provides even after it ends.


In national tests of school readiness, black preschoolers in the United States are not doing as well as white preschoolers. Researchers find black-white gaps not only in achievement and cognitive tests, but also in measures of readiness-related behaviors such as impulse control and ability to pay attention. Could some of these differences in school readiness be the consequence of differences in genetic endowment? In what follows I will review research evidence on this question. (1)

Evidence on the Role of Genetic Differences

To evaluate the research findings on the role of genetic differences in cognitive ability, I begin by drawing a clear distinction between evidence that genetic endowment explains a large fraction of differences within races and evidence that it explains differences between races and ethnic groups. There can be little doubt that genetic differences are an important determinant of differences in academic achievement within racial and ethnic groups, though the size of that effect is not known precisely. Depending on the measure of achievement used, the sample studied, and the age of the subjects, estimates of the share of variance explained by genetic differences within racial and ethnic groups range from as low as 20 percent to upward of 75 percent. However, most estimates, particularly those for younger children, seem to cluster in the range of 30 to 40 percent. The fraction of variance explained by genetic differences in a population is termed the heritability of the trait for that population. (2)

But the heritability of academic achievement within racial or ethnic groups says little about whether genes play a role in explaining differences between racial groups. …

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