The heritability of attitudes: A study of twins

The genetic basis of individual differences in attitudes was examined in a survey of 195 pairs of monozygotic twins and 141 pairs of same-sex dizygoti c twins. A principal components analysis of the 30 attitude items in the su rvey identified 9 attitude factors, of which 6 yielded significant heritabi lity coefficients. Nonshared environmental factors accounted for the most v ariance in the attitude factors. Possible mediators of attitude heritabilit y were also assessed, including personality traits, physical characteristic s, and academic achievement. Analyses showed that several of these possible mediators correlated at a genetic level with the heritable attitude factor s, suggesting that the heritability of the mediator variables might account for part of the heritable components of some attitudes. There was also som e evidence that highly heritable attitudes were psychologically "stronger" than less heritable attitudes.