The science of infidelity and why good people cheat

The science of infidelity and why good people cheat

Picture the end of your relationship. It could be something you've expected for weeks, months, even years. Or it could come as suddenly and unexpectedly as a heart attack. Imagine your significant other with someone else. It's not a pretty picture, is it? Think of the betrayal and the hurt that comes with the thought of your partner in someone else's arms. It's a trauma so damaging that some people never regain their trust, and it can do irrevocable harm to future relationships. Yet millions of people around the world are unfaithful to their partners every year.

Why is this? Our popular perception of cheating tends to be influenced by the melodrama of soap operas; we often view it as a secret and clandestine act of unbridled passion. But by the same token, it's assumed that only those who are unhappy and dissatisfied with their current relationship cheat, and that flirting with other parties is merely a method of expressing underlying angst or emotional strife, a form of compensation for the entitled.

Tabloid newspapers written in the wake of revelations about Tiger Woods' infidelity. Credit: Getty

Similarly, cheaters are invariably portrayed as callous and sociopathic, undeserving of forgiveness or a modicum of understanding. Yet a Victoria Milan survey by Dr Helen Fisher determined that 54 per cent of men and 34 per cent of women who cheated stated that they were "very happy" with their current relationship, despite their indiscretions. So it's clear that our assumptions about cheating might be wrong.

What is it that motivates people to break the social contract? Why do good people, people who are otherwise caring parents, loyal friends and model citizens, screw around behind the back of their loved ones? Is it always a conscious choice between dishonesty and the truth, between love and lust? Or is cheating deterministic? Are cheaters simply automatons governed by a jerry-rig of hormones, passion and animal psychology? Science has been investigating the motivations behind serial adultery and chronic cheaters, and the results are intriguing.

Scholars from the University of California, Los Angeles Centre on Behavior, Culture, and Evolution and the University of New Mexico have determined that women's hormones play a part in cheating. According to a study published in the Journal of Hormones and Behavior, surveyed women were more likely to cheat when they are ovulating, but that ovulation typically only led to cheating if their partners were not sexually active enough. In couples that had sexual intercourse more often, the fertile women were content to stick with their partners.

In light of this data, co-author Elizabeth Pillsworth stated: "Women who are most attractive are most fertile, and they also tend to be the targets of other men to steal them away. I hope the message women get is that they can use this information to realise their biology is toying with their desires and to ask themselves, 'Am I going to let that run my life, my sexual decision-making?'"

By contrast, men are more likely to cheat as a result of what they perceive to be an important milestone: they are just as vulnerable to their body's internal clock, but this has more to do with ageing than a menstrual cycle. In 2014, researchers observing male activity on Ashley Madison, the infamous dating site for people seeking affairs, and discovered that men were more likely to seek extramarital affairs when their age ends in the number nine or the number four: so it seems as though a mid and quarter-life crisis plays a part in the way males seek alternative sexual outlets.

Homepage of Ashley Madison, a dating service for married people to have affairs over. Credit: Getty

Some scientists believe that genetics may play a part in the way we conduct our sexual dalliances and that the way our genes are coded explains how some people end up hooking up. A study from the University of Queensland, published in the journal Evolution and Human Behavior, determined that infidelity is more common among people with specific types of oxytocin and vasopressin receptor genes.

Vasopressin is a hormone which is often released into the hypothalamus gland, and which plays an important part in human social behaviour, sexual motivation and pair bonding. People with developed vasopressin receptors are more inclined to be loyal and trusting, and dependent on their partners. Those with dampened hormonal receptors will experience vasopressin less intensely than others, making them more promiscuous and daring when it comes to sex, but also less attached to their partners and more inclined to cheat.

Dopamine, also known as the "pleasure hormone" also plays a part in determining innate fidelity. This neurotransmitter is released into the bloodstream during or after we participate in things that provide us with pleasure, such as exercising, eating, laughing, playing video games, and most importantly for our purposes, during sexual intercourse at the point of orgasmic release.

Research has determined that those of us possessing long-alleled dopamine receptors are approximately 50 per cent more likely to cheat on their partners than people born with short-alleled dopamine receptors, who have been recorded to cheat around 20 per cent of the time. Not only this, but it has been observed that people with long-alleled dopamine receptors are bigger risk-takers, are more likely to indulge in thrill-seeking behaviours and likely to become addicted to the illicit sex and excitement that cheating provides them.

A billboard written by an angry wife, addressed to her cheating husband. Credit: Getty

In times gone by, when marriage was a solemn oath taken under religious observance, cheating was the last recourse of the desperately unhappy or those with no self-respect. But in the 21st century, where marriage is a more liberal institution that it has ever been, cheating is no less widespread. Infidelity occurs in bad relationships and in good ones. It even happens in open relationships where the terms of sex are negotiated beforehand, and the widespread prevalence of social media means that it is easier than ever for people to keep in touch with those they harbour sexual feelings for.

There are common behaviours and external factors which motivate men and women to cheat, but ultimately it seems as though no matter how biologically or psychologically inclined you are to cheat, every single person in a relationship still has the agency to choose whether to do so.

Featured illustration by Egarcigu