Drug and alcohol use is associated with risky sexual behavior (RSB). It is unclear whether this association is due to correlated liabilities (e.g., third variables influencing both traits), or whether use of drugs and alcohol during sexual decision making increases RSB. This study addresses this question by fitting a series of biometrical models using over 800 twin pairs assessed in early adulthood (m = 25.21 years). Measures included an index of sex under the influence (e.g., frequency that drugs or alcohol affect sexual decision making), number of lifetime sexual partners, and a general measure of substance use. Analyses suggest the covariance among these measures is explained by both genetic and environmental correlated liabilities. The overlap was not specific to sex under the influence, but was shared with a measure of general substance use. Models testing necessary but not sufficient parameters for direction of causation suggest that sex under the influence is unlikely to cause an increase in RSB; more evidence for reverse causation was found.

吸毒和酗酒与危险性行为 (RSB) 相关。尚不清楚这种关联是否归因于相关责任（例如，影响两个特征的第三个变量），或者在性决策过程中使用药物和酒精是否会增加 RSB。本研究通过使用在成年早期（m = 25.21 岁）评估的 800 多对双胞胎拟合一系列生物特征模型来解决这个问题。测量包括受影响的性别指数（例如，药物或酒精影响性决策的频率）、终生性伴侣的数量和物质使用的一般测量。分析表明，这些措施之间的协方差是由遗传和环境相关责任解释的。重叠并非特定于受影响的性别，而是与一般物质使用的衡量标准共享。模型测试必要但不充分的因果关系参数表明，受影响的性别不太可能导致 RSB 增加；发现了更多反向因果关系的证据。