A person's disapproval of noncommittal sex and their condemnation of recreational drug use may have a common genetic basis, suggests a study.
The research, published in the journal Psychological Science, showed that moral views concerning both recreational drugs and openness to non-committed sex are approximately 50 per cent heritable, with the remaining 50 per cent explained by the unique environment.
Furthermore, approximately 75 per cent of the relationship between openness to non-committed sex and moral views concerning recreational drugs was explained by genetic effects, and the remainder was explained by the unique environment.
"People adopt behaviours and attitudes, including certain moral views, that are advantageous to their own interests," said lead author Annika Karinen, a researcher at Vrije Universiteit Amsterdam in the Netherlands.
"People tend to associate recreational drug use with non-committed sex. As such, people who are heavily oriented toward high commitment in sexual relationships morally condemn recreational drugs, as they benefit from environments in which high sexual commitment is the norm," she added.
The researchers also found substantial overlap in the genetic effects underlying both factors - namely, that approximately 40 per cent of the genes underlying openness to non-committed sex also underlie moral views concerning recreational drugs.
"These findings suggest that the genetic effects that influence openness to non-committed sex overlap with those that influence moral views concerning recreational drugs," said Karinen.
"Important parts of hot-button culture-war issues flow from differences in lifestyle preferences between people, and those differences in lifestyle preferences appear to partly have a genetic basis."
To understand the hereditary and environmental factors, the team surveyed 8,118 Finnish fraternal and identical twins to examine how open they were to recreational drug use and to sex outside of a committed relationship.
The researchers then compared fraternal and identical twin pairs to assess the extent to which condemnation of recreational drugs, openness to non-committal sex, and the relationship between the two was explained by genes; the shared environment such as growing up in the same household or community; or unique experiences and environments not shared by the twins.