One twin study has investigated this issue using a GxE approach. Heath, Jardine, & Martin (1989) found that marital status moderated the manifestation of genetic influences on alcohol consumption among female twins from Australia. Genetic influences explained a greater proportion of the variance in weekly alcohol consumption among unmarried females (younger cohort, 60%; older cohort, 76%) compared to married females (younger cohort, 31%; older cohort, 46–59%). There was no evidence for shared environmental influences, and the remainder of variance was attributable to individual-specific environment.
