Commentary on Verweij et al. (2016): Conduct problems and substance use-genetic and environmental perspectives on sex differences

Genes influence the covariance between conduct disorder (CD) problems and substance use in males, but shared environment is more important in females. We now need to consider: (a) how genetic influences on CD affect correlations across substances from early to later stages of involvement; (b) whether polygenic liability to CD and substance use overlap; (c) environmental pathways of vulnerability (e.g. peers) in females; and (d) sex effects derived from opposite-sex twin pairs.