Between‐ vs. within‐family analyses of the correlation of height and intelligence

Abstract

Small but consistently positive correlations between standing height and general intelligence (the unrotated first principal component across the battery of cognitive tests) were found across sexes, racial/ethnic groups (Americans of European vs. Americans of Japanese ancestry), and generations in data from the Hawaii Family Study of Cognition. Sibling data produced significant height‐intelligence correlations for sibling pair means (i.e., between‐family differences) but not for within sibling pair differences. The lack of within‐family height‐intelligence correlations suggested that the two traits were linked due to cross‐assortative mating and/or between‐family environmental influences (e.g., nutrition) affecting both traits. Some evidence for both of these explanations was found.