Decomposition of Mean Sex Differences in Alcohol Use Within a Genetic Factor Model

A wealth of literature suggests that normative and heavy alcohol consumption continue to follow a historical pattern of greater prevalence among males as compared to females. Some prior research suggested that sex-specific factors might explain some of this gender gap. Generally speaking, though, more recent studies have indicated that the sources of differences for most complex traits, both genetic and environmental, are similar for males and females. To the best of our knowledge, however, no studies have tested whether genetic and environmental factors common to both sexes are more often expressed in males, on average, thereby accounting for some of the mean sex difference in alcohol use. The current study used nationally representative data from American twin respondents and a multiple group genetic factor model with a mean structure to address this gap in the literature. Results provide no evidence of sex differences in covariance structure and suggest that genetic and nonshared environmental influences common to both sexes largely explain why male alcohol use is more frequent and severe, on average, than is female use. In contrast, shared environmental influences seem to play a less important role. We discuss our findings in the context of the existing literature and chart out directions for future research.