Goldman et al. recently reviewed large unselected twin studies of substance use disorders (Goldman et al., 2005). Weighted mean heritability estimates were as follows: cannabis use disorder (abuse or dependence), 43% (five studies); sedative use disorder, 51% (three studies); stimulant use disorder, 40% (three studies); cocaine use disorder, 72% (three studies); and alcohol dependence, 56% (five studies). We identified one more recent eligible study of cannabis use disorder (Kendler et al., 2006a), and, in this study, the heritability estimate was higher than most previous studies (77%); including it (total of 6 studies), the weighted mean heritability estimate was 48%.
