Alcohol use disorder (AUD) is among the most common of psychiatric syndromes (Grant, 1997) and is often accompanied by significant psychosocial dys-function, a range of medical co-morbidities and substantially increased mortality (Secretary of Health and Human Services, 1997). It has been known since classical times that AUD is familial (Bynum, 1984) and this has been verified by more modern family studies (Cotton, 1979). Since 1960, a series of twin (Kaij, 1960; McGue et al. 1992; Reed et al. 1996; Heath et al. 1997; Prescott et al. 1999; True et al. 1999; Knopik et al. 2004; Magnusson et al. 2012) and adoption (Goodwin et al. 1973, 1977; Bohman et al. 1981; Cloninger et al. 1981; Cadoret et al. 1987; Sigvardsson et al. 1996) studies have attempted to determine the relative roles of genetic and environmental factors in the etiology of AUD. While these studies have been reviewed qualitatively several times (e.g. Heath, 1995; Prescott & Kendler, 1995; Dick & Bierut, 2006), we are unaware of any quantitative meta-analysis.
