Though twin registries have historically consisted largely of individuals of European descent, a limited number of twin studies have attempted to estimate heritability in AA twins for alcohol use phenotypes, including alcohol abuse and dependence, 11 age of first use,19,20 and problem use.20 The study on alcohol dependence comes from the Washington University Twin Study of Alcoholism which included approximately 50 AA twins with alcohol dependence diagnoses. The latter two studies focusing on AA twins come from the Missouri Adolescent Female Twin Study (MOAFTS) which included approximately 240 AA twins. This sample was limited to female twins only. These studies have found both differences and similarities across populations. Twin correlations among individuals diagnosed with alcohol abuse or dependence suggested stronger genetic influences for both male and female EA twins (and correspondingly a greater importance of the environment in AA individuals), though the sample size was too small to produce accurate estimates for AA twins.11 Additive genetic factors contributed to age of first drink and problem alcohol use in both EA and AA twins.20 Estimates of genetic variance were greater for
