Studies clearly have shown that both genetic and environmental factors contribute to the risk for alcohol dependence, and it is likely that the interplay between these factors is critical for determining the risk for alcohol abuse and dependence. Advances in genetic technologies already have allowed researchers to explore the genome in ever greater detail, and with the advent of whole-genome sequencing, complete delineation of genetic variation soon will be available. In contrast, our understanding of the critical environmental factors influencing alcohol use disorders remains inadequate and is an area of active research. One of the challenges is how to define the environment, which may include family, peer, and societal influences; other exposures; personality or psychiatric factors (which also have genetic components); and many more, most of which change over time. Furthermore, the influence of these factors on the risk of alcohol use disorders varies within the lifespan (Sher et al. 2010; van der Zwaluw and Engels 2009).
