Female infidelity: write off the genes?

Cheating is worse than cloning and suicide. In any case, according to residents of the United States, where 91% of citizens condemn treason.¹ However, this very condemnation does not in any way prevent Americans, like all other inhabitants of our planet, from regularly cheating on partners. Polls from the University of Chicago Research Center show that the percentage of unfaithful spouses has remained stable over the years and is just over 20% for men and 10-15% for women.

And if male behavior can be explained by the requirements of evolution, then with female everything is much more complicated. After all, the more partners a man manages to fertilize, the higher his chances of fulfilling his biological destiny – to leave offspring. But for women, this logic does not apply: the number of partners has practically no effect on the likelihood of becoming pregnant. So why, you ask, do they need it? Clinical psychologist Richard A. Friedman has analyzed the most striking research on this topic.²

Spray of trust

Speculation that infidelity may be related to genetics has been expressed for a long time. Candidates for the unenviable role of initiators of adultery were also named – the genes responsible for the synthesis of the hormones vasopressin and oxytocin. By themselves, these hormones are not only associated with sexual behavior. To a greater extent, they influence the formation of a sense of trust and a tendency to stable social ties (without which, however, fidelity is also hardly possible). For example, in one study, participants were asked to play an economic game. They acted as investors who invested conditional funds in certain projects. And in some cases they received generous dividends, and in a number of cases they lost all their investments. Before the start of the game, all participants took a drug that increases the level of oxytocin. More precisely, only half of the subjects took the real drug, the other half received a placebo.

The results were impressive. Those players who took placebos were much more cautious, preferring to invest only in reasonable projects. And those who received oxytocin invested in the most unrealistic undertakings, believed the most ridiculous promises and were not at all embarrassed by constant losses.³ Other studies have found that vasopressin also has an effect on social behavioral strategies.

Potentially, this allows the use of oxytocin and vasopressin in the treatment of serious mental disorders. Thus, autism, for example, is associated with a lack of confidence, and there is preliminary evidence that oxytocin administration brings some positive results in this situation. In contrast, a rare genetic disorder known as Williams syndrome is characterized by an overly gullible and striving to establish connections without any critical attitude towards strangers. The level of oxytocin in such patients is on average three times higher than normal. And blocking its synthesis also seems promising.

Read more:

• Dogs love it too

However, these same studies have generated a lot of speculation. For example, the fact that adding oxytocin to perfumes or air fresheners (and the hormone is absorbed primarily intranasally) will help to become more attractive or facilitate the course of difficult negotiations. The idea is doubtful, and in any case, humanity has not yet reached the creation of a “trust spray”.

Don Juan mice

However, back to change. Psychologist Thomas R. Insel, who heads the US National Institute of Mental Health, was one of the first scientists to pay attention to the effects that vasopressin and oxytocin levels have on sexual behavior in animals.

Insel studied two closely related species of rodents – mountain and prairie voles. With all the similarities, these animals are radically different in their views on family life. Prairie voles are monogamous, after sexual contact they form pairs and raise offspring together in minks. Mountain voles, on the other hand, demonstrate reprehensible promiscuity, preferring one-time sexual contacts. Thomas Insel found that this difference may be due to vasopressin receptors.⁴

In mountain and prairie voles, they are located in completely different areas of the brain. And if in the prairies they are concentrated near the center of pleasure, then in the mountains – mainly in the amygdala (almond-shaped body) – an area associated with feelings of anxiety and fear. Thus, the production of vasopressin, which encourages trust and social bonding, stimulates the pleasure center in prairie voles—and they genuinely enjoy their monogamy. And in their mountain relatives, the same vasopressin stimulates experiences of anxiety and fear – is it true here!

Not only that, further research has established an even more amazing thing. By using viruses as a means of “delivering” the genes responsible for the synthesis of vasopressin, scientists were able to artificially activate its receptors near the pleasure center in the brain of male mountain voles. And those known for their Don Juan behavior suddenly became monogamous. In female mountain voles, the same effect was produced by artificial activation of oxytocin receptors.

40 percent change

Is that how it is with people? Imagine yes. Well, at least it looks like it. This is evidenced by a study by Australian psychologist Brendan P. Zietsch. Which, by the way, overcame half the world for the sake of his work, going to Finland. His study involved 7400 Finnish twins and their relatives. A prerequisite was the experience of partnerships for at least a year.

Zitch found that during that year, 9,8% of men and 6,4% of women had sex with two or more partners. And then he traced the relationship between cases of infidelity and 5 variants of mutations in the gene encoding the production of vasopressin in the organisms of unfaithful partners. And he found that up to 40% of cases of female infidelity can be caused precisely by genetics.⁵

Read more:

• “Is it possible to talk about betrayal in a new way?”

Brendan Zitch’s research is recognized as the largest and most thorough on this topic to date. However, it hardly provides a definitive answer to the question of the causes of infidelity. If only because no effect of oxytocin on either men or women was found in Zitch’s work – although such an effect was noted in several previous studies. Yes, and with the history of mountain voles, all this somehow does not fit very well.

But that’s not the point. No matter how far science has gone in the study of this topic, humanity is unlikely to come to the conclusion that since betrayal is genetically determined, one can only come to terms with it, Richard Friedman is sure. Of course, we are not in a position to choose suitable genes for ourselves – at least not yet. However, to control the emotional impulses provoked by certain genes is the direct responsibility of a reasonable person. And this also applies to women.

¹ According to Gallup sociological research in 2013, gallup.com.

² Richard Friedman is Professor of Clinical Psychiatry at Cornell University Medical School (USA), author of several dozen scientific papers. For more information, see his article “Infidelity Lurks in Your Genes” on The New York Times website (nytimes.com).

³ T. Baumgartner et al. “Oxytocin Shapes the Neural Circuitry of Trust and Trust Adaptation in Humans”. Online publication on the website of the journal Neuron dated May 21, 2008.

⁴ T. R. Insel, L. E. Shapiro «Oxytocin receptor distribution reflects social organization in monogamous and polygamous voles». Neurobiology, vol. 82, July 1992.

⁵ B. P. Zietsch et al. «Genetic analysis of human extrapair mating: heritability, between-sex correlation, and receptor genes for vasopressin and oxytocin», Evolution and Human Behavior, October 2014.