The ubiquity of g

Abstract

We obtained the g-loading (unrotated first principal-component loading) of each of the cognitive ability measures used in the Hawaii Family Study of Cognition (HFSC) for each of the three major ethnic groups (Americans of European ancestry (AEA), Americans of Japanese ancestry (AJA) and homeland Koreans) who took part in the HFSC. The degree to which given tests (corrected for reliability) loaded on g was highly correlated with the association of cognitive test scores with the educational and occupational attainments of members of both the parent and offspring generations, with the degree of resemblance of spouses and biological relatives, and with the degree to which parental education and occupation predicted offspring cognitive test performance. For AEA and AJA families g was not found to be related to degree of mean within-sibship skew for each cognitive test, but was positively correlated with the degree of ‘hybrid vigor’ manifested by offspring of cross-ethnic matings. The above results suggest that g, as opposed to the non- g components of intelligence, is more influenced by additive genetic factors, although this is confounded by assortative mating for g, but provide only weak support for the hypothesis that g is more influenced by directional genetic dominance. While the correlations were similar in directionality for all groups, they varied considerably in magnitude, possibly because the groups differed substantially in environmental histories.