Many people share similar morals as their parents. This also includes attitudes towards the use of recreational drugs and towards sex without a permanent bond. In order to find out to what extent these moral concepts are genetically anchored and whether they are related, researchers have now surveyed thousands of pairs of twins and their siblings. The result: genes have a major influence on attitudes towards drugs and casual sex. Moreover, attitudes on both issues can probably be traced back to a common genetic basis.
Psychologists assume that many of our moral ideas are ultimately determined by self-interest. Previous studies have shown that people who are hungry are more likely to advocate social welfare, and those who are physically strong are more likely to have moral systems that reward strength. But what benefit do people get when they condemn other people using drugs in their free time? One thesis is that drug use is associated with excessive sexual behavior, which in turn poses a threat to people who invest heavily in relationships. However, to what extent the moral concepts in the areas of drugs and sexuality are related and whether they are more caused by our genes or by our environment, has so far been unclear.
Attitudes towards sex and drugs
A team led by Annika Karinen from the Free University of Amsterdam has now investigated these questions in a large twin study. To this end, the researchers asked almost 6,000 monozygotic and dizygotic twins and over 2,000 siblings of twins about their attitudes towards drugs and sex. The test subjects rated, for example, whether they find it morally reprehensible for someone to consume marijuana at a party, whether they can imagine non-binding sex without a fixed bond, and to what extent they are disgusted with certain sexual activities such as oral intercourse. In addition, they filled out questionnaires about their religious and political orientation.
With the help of statistical methods, Karinen and her colleagues examined correlations between the answers and also evaluated how similar the answers of identical twins were compared to those of siblings or dizygotic twins. The assumption here: since identical twins share 100 percent of the genetic material, while dizygoti and siblings share only 50 percent, higher matches between identical twins indicate a genetic influence. Based on the study, the researchers were able to draw conclusions about the proportions of genetics, the common environment in the same parental home and the same community, and unique experiences that an individual does not share with his siblings.
Genes more important than shared experiences
The result: “The twin modeling suggests that family-internal similarities in both drug condemnation and sexual strategy can be traced back to shared genetic rather than shared environmental influences,” the researchers said. They conclude from the fact that the answers of identical twins to the moral questions were much more in agreement than the answers of dizygoti twins and other siblings. The common parental home therefore only plays a subordinate role. Instead, according to the study, around 50 percent of moral views regarding drugs and sex are hereditary, while the remaining 50 percent of the deviation is explained by the unique social environment.
Consistent with previous surveys, there were clear links between openness to non-committal sex and attitudes towards drugs: “Our results suggest that people who care about high levels of attachment during sex are more likely to condemn recreational drug use, even when we are Calculate personality traits, religiosity and political ideology, ”write Karinen and her colleagues. According to the researchers, 75 percent of this correlation can be explained by genetic effects, with 40 percent of the genes underlying openness to non-committal sex also influencing moral views about recreational drugs.
Morality in the genes
“Important parts of the controversial issues of the Kulturkampf result from differences in people’s lifestyle preferences, and these differences seem to have a genetic basis in part,” says Karinen. An interesting question in this context is to what extent this also applies to other moral concepts apart from drugs and sexuality. “Such findings, in conjunction with those reported here, can help elucidate the biological factors that underlie our moral and political psychology,” the researchers said.
Source: Annika Karinen (Free University of Amsterdam, Netherlands) et al., Psychological Science, doi: 10.1177 / 0956797621997350