Because alcoholism is a highly heritable condition, children of alcoholics, especially sons, are at much higher risk than the general population for developing the disorder. Furthermore, secular trends are apparent for both sons and daughters of alcoholics, such that alcoholism has become more prevalent over time, increasing the morbid risk in offspring of alcoholics. Increases in prevalence of disorders known to be associated with alcoholism, such as conduct disorder, depression, and drug abuse, have also been found in younger cohorts, as well. At the genetic level, alcoholism appears to be heterogeneous, raising the possibility that alcoholism may be a product of numerous different kinds of gene-environment interactions. Further advances in our understanding of alcoholism will come from molecular genetic studies and longitudinal studies of high-risk populations.