The heritability of alcohol abuse and dependence: a meta-analysis of behavior genetic research.

A meta-analysis was performed on 50 family, twin, and adoption studies in which problem drinking and alcohol dependence served as the primary criterion measure. The results showed that far from being an established "fact," the genetic foundations of alcohol misuse are modest and heterogeneous. A weighted mean phi effect size of 0.12 (95% Confidence Interval = 0.11-0.12) was obtained for the total sample of 72 effect sizes. Four potential moderator variables (proband gender, sample nationality, pattern severity, year of publication) were examined with outcomes confirming that the heritability of alcohol misuse is stronger in males and in studies employing more severe definitions of abuse (alcoholism, alcohol dependence). When the effect size measure was restricted to studies using male subjects with more severe diagnoses of alcohol misuse, the unweighted mean phi effect size was only 0.18 (95% Confidence Interval = 0.15-0.21), with an even smaller weighted mean phi effect size of 0.15 (95% Confidence Interval = 0.12-0.18); results which indicate an upper limit of 30-36% for the heritability of alcohol misuse.