Genetics of alcoholism: effects of migration on concordance rates among male twins.

We have extended linkage of the population-based Finnish Twin Cohort to alcohol-related hospital discharge data through 1985. The sample included 10,680 individual male twins > or = age 30 at time of linkage; 269 of these twins (2.5%) had received an alcohol-related hospital diagnosis. Twin analyses confirm significant genetic variance in alcohol-related disorders, but suggest that concordance for these disorders is greater for twins living within limited geographic areas, perhaps due to restricted social mobility among those who abuse alcohol.