During the 20th century, many researchers studying heredity sought to apply their findings in the arena of mental health and human (mis)behavior. Many of these have examined, from the perspective of heredity and genetics, the desire to drink and its consequences. In this paper, the author examines hereditary explanations of alcoholism in two historical snapshots: the early decades of the 20th century and in the 1990s. Two things come to light. First is the persistence of an“entrepreneurial spirit,”and second is a (...) remarkable failure to take into account the many-leveled heterogeneity in causes of alcoholism. The author describes some sources of this heterogeneity and showshow epistemological problems that arise from it suggest the failure of genetic accounts to consider the social dimensions of disease classification, observation, and diagnosis that form the very basis of the designation “alcoholic.”. (shrink)