There is substantial evidence from latent variable genetic approaches using twin samples that genes contribute to variation in alcohol consumption levels. In general, studies find that approximately 30% to 60% of variance in alcohol consumption is influenced by genetic factors (Heath and Martin, 1994). Linkage and GWA studies have also identified chromosomal regions (Edenberg and Foroud, 2006; Long et al., 1998; Prescott et al., 2005; Reich et al., 1998; Wyszynski et al., 2003) and genes (Johnson et al., 2006; Uhl et al., 2008) associated with alcohol-related traits. However, they have typically used samples ascertained for a family history of substance abuse. Is it therefore reasonable to expect to find similar evidence of genetic influence in samples unselected for problems related to substance use?
