Studies of familial alcoholism: a review.

Recent studies demonstrate the existence of familial and nonfamilial types of alcoholism. The familial type is characterized by an early age of onset and a severe course. Nonfamilial alcoholism is more often associated with other adult psychiatric disorders. Adoption and twin data suggesting genetic influences in some forms of alcoholism are reviewed. Findings are summarized from studies comparing familial with nonfamilial alcoholics, and from high-risk studies in which sons of alcoholics are compared with sons of nonalcoholics. Both types of studies show important differences between familial and nonfamilial alcoholics.