Sex, drugs, and genes: Illuminating the moral condemnation of recreational drugs

Over the past decade, evolutionary psychologists have proposed that many moral stances function to promote self-interests. At the same time, behavioral geneticists have demonstrated that many moral stances have genetic bases. We integrated these perspectives by examining how moral condemnation of recreational drug use relates to sexual strategy (i.e., being more vs. less open to sex outside of a committed relationship) in a sample of Finnish twins and siblings (N = 8,118). Twin modeling suggested that genetic factors accounted for 53%, 46%, and 41% of the variance in drug condemnation, sociosexuality, and sexual-disgust sensitivity, respectively. Further, approximately 75% of the phenotypic covariance between drug condemnation and sexual strategy was accounted for by genes, and there was substantial overlap in the genetic effects underlying both drug condemnation and sexual strategy (rg = .41). Results are consistent with the proposal that some moral sentiments are calibrated to promote strategic sexual interests, which arise partially via genetic factors.