Sons of alcoholic parentage, adopted in infancy, were compared with their brothers who were raised by the alcoholic parent. Both the adopted and nonadopted sons had high rates of alcoholism (25% and 17%, respectively), but the difference was not statistically significant. The two groups also had comparable frequency of alcohol problems. The nonadopted sons differed from the adopted sons in age (older) and belonging to a lower socioeconomic class.
Length of exposure to the alcoholic parent was not associated with the development of alcoholism. However, severity of the parent's alcoholism, as inferred by number of hospitalizations, was positively related to alcoholism in the offspring. The results suggested that environmental factors contributed little, if anything, to the development of alcoholism in sons of severe alcoholics, in this sample.