Do individual differences in sociosexuality represent genetic or environmentally contingent strategies? Evidence from the Australian twin registry

Although men are substantially more interested than women in casual sex, th ere is ample variation in this trait (sociosexuality) within both sexes. On e theory hypothesizes that within-sex sociosexual variation results from ge neric variation maintained by frequency-dependent selection. if so, sociose xuality should be substantially heritable. A competing theory is that child ren acquire their mating strategy after observing their parents' relationsh ip. By this theory, sociosexuality should reveal a strong shared environmen tal component. The authors studied genetic and environmental influences on sociosexuality using a large, representative volunteer twin sample. Parenta l marital instability was modestly associated with sociosexuality, but this could have been due to either genetic or environmental factors. Consistent with genetic theory, familial resemblance appeared primarily due to additi ve genetic rather than shared environmental factors.