Being cheated on by a partner is a jarring experience which most people attempt to avoid at all costs. However, while some believe they can spot the signs of a cheater, infidelity may have more to do with our biology than our behaviors. While circumstances certainly factor into cheating, the biology of our brains and bodies may play a larger role in infidelity than we think. These are the scientific factors which make people more prone to cheat on their partners.

The surprising link between dopamine and cheating

Can the properties of a cheater be boiled down to their DNA? Believe it or not, our alleles might play a major role in infidelity. The largest gene influence on cheating behaviors seems to be our dopamine receptors. Dopamine is a neurotransmitter which plays a massive role in the functioning of our brains and bodies, including contributing to healthy emotional reactions. While our dopamine receptors are stimulated in our everyday lives by activities such as exercising and eating, the length of the D4 gene seems to play a role in how prone we are to cheating on our significant others.

A 2002 study highlighted by AsapSCIENCE showed that a whopping 50% of people who possess a long version of the allele of the D4 dopamine-receptor gene had been unfaithful to their partner. In comparison to the 22% of cheaters with the short allele, the correlation between cheating and the long D4 allele seems undeniable. Unsurprisingly, those with the long alleles also seemed to struggle more with addiction and impulsivity, perhaps playing a role in their unfaithful behaviors.

The impact of a mutated gene

Another biological factor that seems to affect cheating is an individual’s vasopressin receptor gene. Vasopressin is a hormone that our bodies produce that has a significant effect on empathy, trust, and sexual bonding in humans and animals. The University of Queensland in Australia performed a study examining the correlation between the vasopressin receptor gene and a person’s tendency to seek intimacy outside of a monogamous relationship. Observing close to 7,400 twins who had been in long-term relationships, a Dr. Brendan P. Zietsch explored the impacts of a mutated vasopressin receptor gene on human sexual infidelity. His findings reaffirmed his beliefs that the two were strongly correlated, particularly in women.

Women showed a strong correlation between a mutated version of the gene and cheating behaviors. Of the 6.4% of women who cheated during the study, an incredible 40% of them had a mutation of the vasopressin gene. Surprisingly, the men in the study seemed unaffected by a variation in their vasopressin gene. 9.8% of men in the study cheated on their partner, yet these behaviors seemed to show no correlation with a mutated vasopressin gene. However, vasopressin is also thought to affect partner bonding, which can impact the contentment of men in their relationships, leading to thoughts and actions of infidelity over time.

The role of our psychology

On top of our physical biology, our psychological characteristics also play a major role in how likely we are to cheat on our partners. One’s personal psychology is shaped by both their genetics/biology and elements of their culture, childhood, and circumstances. One of the largest factors when it comes to the psychology of cheating is that the cheater feels as if though they are entitled to be unfaithful. Those who cheat have often been proven to psychologically struggle with empathy, narcissistic thoughts, impulsivity, and/or self-destructive behaviors. Whether these are influenced by mental illness or not is up for debate, yet it’s clear that mental health plays a role in infidelity.

In a UMD-led study later published in the Journal of Sex Research, researchers asked for a self-report from people who had cheated describing their reasoning for their infidelity. Many reported that they were angry or falling out of love with their partner, that they felt neglected by them, or that they were attempting to boost their self-esteem through sleeping with a variety of partners. These psychological factors — possibly attributable to one’s dopamine and vasopressin production — seemed to play a massive role in the cheaters’ decisions to stray from their partners.