reflection of parenting practices (Latendresse et al. 2010), drinking family members (Poelen et al. 2007; Mcgue et al. 1996), or religious upbringing (Kendler and Myers 2009). The home environment that parents provide for their children might also in part reflect the genes the parents transmit to their children. If parents transmit both genes and environment—referred to as genetic and cultural transmission—this induces a passive correlation between G and C (e.g., Rijsdijk and Sham 2002). Passive G–C correlation might for instance occur if one of the parents suffers from AAD which also creates an environment in which the availability of alcohol at home is more likely. In addition to familial influences originating at home, the shared environmental effects in twins might also reflect the influence of peers’ alcohol use when twins share the same peer group (Fowler et al. 2007).
