Digging deeper, scientists have examined the impact of religion and social class on rates of adultery. Religion, it turned out, made no difference at all — no matter what people professed to believe, it failed to stop some of flirting and transgressing boundaries....
Adultery, it seems, is an innate part of human behavior. That means that it probably has some biological predisposition… What happens in these cases where our new brain (neocortex) is unable to stop the desires of the old brain (reptilian brain and limbic brain, see Newsletter 1) even where people are beheaded or stoned for it?...
One of them is a set of genes in the Vasopressin System. Vasopressin is a hormone, formed and stored in the pituitary glands, before being released into the bloodstream and possibly directly into the brain, where it is believed to play a role in social behavior, sexual motivation and pair bonding.
Swedish scientists investigated how the presence of the vasopressin gene is related to the degree of attachment to a mate. Amongst 552 men, some had no copies of this gene, someone had 1 or 2 copies. Result: the more copies of the gene you have, the less stable your primary relationship is. This study was not focused on adultery; they were studying the stability of the partnership, which can certainly lead to adultery if it is unstable.
This field of work is relatively new, but scientists think other ‘adultery genes’ are probably involved. In another recent study, for instance, a direct link was found between specific genes in the dopamine system (dopamine is a neurotransmitter that controls the brain’s reward and pleasure centers) and a higher frequency of sexual infidelity.
There are also some genes and the immune system that seem to play a role in adultery. We tend to be drawn to people who have a different set of gens in the part of the immune system and, in fact, when you are with a partner who is very similar to you in this part of the immune system, women particularly are more likely to cheat, specially when they are ovulating (when they are more likely to get pregnant).
In short, for millions of years there were some reproductive benefits, not only from the formation of a bond, but also from its transgression. The man ensured with extramarital sex the propagation of his DNA to the next generation. The woman insured herself with the extramarital man an "extra" protection, an insurance policy: the fact of having children from different fathers increased the probability that most of them would survive and that one of the fathers would take care of her and all her children.
As we can see in this chapter, this biological, environmental and social behavioral conditioning over millions of years has influenced our genes through "epigenetic modifications" of DNA. These chemical modifications can have sex-specific effects, can silence chromosomes and sex hormones, and can cause epigenetic changes in the brain, leaving each of us with a tremendous drive to follow love and create a union, but also with some susceptibility to cheating.
Questions for Reflection:
- What about you? Have you ever been attracted to someone else outside of your marriage? How have you felt about that? What positive aspect do you find in it?
- How do you feel knowing that attraction to people outside of marriage is on a big extend governed by our genes?
- Does it help you to expand your understanding of this painful issue of disloyalty?
In the next blog, we will analyse the birth of romantic love from a historical point of view, what dilemmas were created by the redefinition of "marriage/partnership" in the last 150 years and we will make an approach to the definition of infidelity.
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Sources / Reading suggestions:
- “Anatomy of Love: A Natural History of Mating, Marriage and Why We Stray” - Helen Fisher
- “Psychoneuroendocrinology” - Rilling J.K.