Familial resemblance for general cognitive ability in the Hawaii Family Study of Cognition.

Abstract

Familial correlations for general cognitive ability wer estimated for three ethnic groups tested in the Hawaii Family Study of Cognition (Americans of European, Japanese, and Chinese ancestry). Assuming multivariate normality of family data, separate observed covariance matrices were computed for families of different size, ethnicity, and child's gender and then equated to their expectations using a log-likelihood ratio statistic. Resulting maximum-likelihood estimates of familial correlations are highly similar to previously reported product-moment and intraclass correlations; however, standard errors for the maximum-likelihood estimates are somewhat smaller. More importantly, the estimation procedure employed in the present study facilitates tests of alternative hypotheses. Using this approach, hypotheses of homogeneity of familial correlations among the three ethnic groups and of homogeneity among the various parent-offspring correlations (mother-son, mother-daughter, father-son, father-daughter) and sibling correlations (son-daughter, son-son, and daughter-daughter) were rejected.