The first adoption-study evidence for an important genetic contribution to alcoholism risk was produced in Scandinavia. In Copenhagen, Denmark, Goodwin and colleagues (1973, 1974, 1977a,b) used official registries to identify biological parents who had histories of alcoholism and who had given up a child for early adoption by nonrelatives. The researchers used biological parents who had no known histories of alcoholism but who also had given up a child for early adoption as control subjects. Interviews were conducted with adult sons and daughters of both groups to determine the prevalence of alcoholism among them. The researchers speculated that if the genetic contribution to alcoholism were important, the rates of alcoholism should be higher in the adopted-away offspring of the alcoholic biological parents than in the adopted-away offspring of the control parents.
