We examined in this article the herdability of drug addiction. Family, twin and adoption sudies reviewed allow us to support the thesis of an important genetic component in drug addiction. The trasmission of this herdability occurs through a biological vulnerability associated to environmental factors, in a model called epigenetic. We also discuss the relationship between biological vulnerability and high-risk phenotypes, focusing on alcohol and cocaine. At the end, we present molecular genetic studies associated with these disorders.
Drug addiction; genetic epidemiology; molecular genetics; alcohol; cocaine; epigenetic model