School-level genetic variation predicts school-level verbal IQ scores: Results from a sample of American middle and high schools

Research has consistently revealed that average IQ scores vary significantly across macro-level units, such as states and nations. The reason for this variation in IQ, however, has remained at the center of much controversy. One of the more provocative explanations is that IQ across macro-level units is the result of genetic differences, but empirical studies have yet to examine this possibility directly. The current study partially addresses this gap in the literature by examining whether average IQ scores across thirty-six schools are associated with differences in the allelic distributions of dopaminergic polymorphisms across schools. Analysis of data drawn from subjects (ages 12–19 years) participating in the National Longitudinal Study of Adolescent Health provides support in favor of this perspective, where variation in school-level IQ scores was predicted by school-level genetic variation. This association remained statistically significant even after controlling for the effects of race.

Research highlights
► This study examined whether genetic variation at the school-level was related to variation in IQ schools aggregated to the school level.
► The results revealed that schools that had higher scores on a dopamine scale were, on average, the same schools that had lower IQ scores.
► Additional analysis revealed that this association remained statistically significant even after controlling for the effects of race.