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How Normative vs Non-normative Sexual Behaviors Differ in Heritability and Associations with Personality, Peers, and Substance Use
There is substantial variability in the timing and the range of adolescent sexual behaviors (e.g., dating, sexual intercourse). Across a series of studies using a longitudinal twin sample assessed at ages 11, 14, and 17 (N = 3762), we examined how the normativeness of sexual behaviors (i.e., their frequency and level of social approval) was related to their heritability and correlates. Normative sexual behaviors (e.g., dating) were more heritable, and associated with extraversion, largely via shared genetic influences. Non-normative sexual behaviors (e.g., early intercourse, pregnancy) exhibited large shared environmental influences that also accounted for their associations with low conscientiousness and low agreeableness, antisocial peers, and substance use. These results suggest two person-situation processes contributing to adolescent sexual development. One is largely genetically mediated for more normative behaviors and their correlates such that for behaviors with fewer constraints, genetically-based differences among youth in sexual propensities are able to manifest. The second relates to non-normative sexual behaviors such that shared environmental influences shape the emergence (or suppression) of riskier and less socially approved sexual behaviors. Importantly, these same environmental influences also account for much of the variation in toward norm violation, antisocial peer affiliation, and substance use, and suggests environmental targets for intervention in middle adolescence that could reduce risky sexual behavior and other adolescent problem behaviors.