Genetic and environmental evidence does not support this notion. With the exception of an aldehyde dehydrogenase variant (ALDH2*2) in East Asian populations, alleles of large effect have not been identified.37 Although a number of common alleles have been identified through genome-wide association methods, these are of very small effect.38 Thus, like other complex diseases such as diabetes39 and traits such as height,40 alcohol use is characterized by polygenic inheritance. When genetic influences are weak, numerous, and common, they interact and aggregate to form a quantitative continuum of risk in the population, making it unlikely that qualitatively distinct groups will arise as a function of polygenetic risk.
