Twin studies underline the significance of the genetic influences. Overall, the comparison of monozygotic (MZ) and dizygotic (DZ) twins has shown a greater concordance for addiction in the monozygotic group. Twin studies in Sweden reported a 54% alcoholism prevalence between MZ and 28% in DZ twins. Epidemiological studies in groups of twins have shown that the risk of hereditary transmission for alcoholism ranges between 0.52 and 0.64 with no significant difference between the sexes [5]. However, there are different genetic influence for the inheritance of alcohol abuse and different for alcohol dependence. The liability for alcohol abuse in male subjects is attributed to genetic and shared environmental factors. For female alcohol abuse, liability is attributed to shared and non-shared environmental factors with no evidence of genetic influence [6] though women might carry a lower genetic risk for alcohol dependence [7]. Overall, the results of the majority of twin genetic studies support the existence of significant genetic factors that predispose individuals to the development of alcohol related problems [8,9].
