Why You Were Born To Cheat On The Person You Love (Yes, Really)

Is it written in our DNA that we'll cheat on the person we love?

Last updated on Apr 28, 2024

People born to betray eachother, cheating Srdjan Randjelovic | Shutterstock

If there's one thing we can all agree on, it's that cheating on your partner is just plain wrong, right? Those of us who have been on the receiving end of betrayal know how incredibly gut-wrenching and downright devastating it is. Just raise the topic in a crowded room and watch how quickly people spout off about how infidelity is immoral, cruel, and unforgivable.

Not only have I been cheated on, but many of my dear friends (both men and women) have had their hearts and marriages shattered by a cheating partner.  On the other hand, I also know just as many people who are the ones guilty of doing the cheating. In every single case, the act ultimately caused nothing but pain and misery for all parties involved. Even the ones who strayed admitted their regret over cheating and quickly realized that the "perks" were little more than fleeting illusions that left them feeling empty and worse about themselves than ever before.


And yet, so many people still do it. The question is why? Why do people cheat? We’re all pretty tired of hearing the blame-based reasons modern relationship experts give us: He cheated because you gained weight. He was bored, because he didn’t feel appreciated. She cheated because you don’t romance her anymore. After all, she felt ignored and neglected, because you didn't make her feel like a woman anymore. Well, if that's all true, how do you explain the latest research which clearly states that even happily married people cheat?

To sort through the confusion, I turned to the true expert on this issue, biological anthropologist Helen Fisher, and found some sobering information in her acclaimed book Anatomy of Love: A Natural History of Mating, Marriage and Why We Stray. The answer to the age-old question of "Why do people cheat?" is an incredibly bitter pill to swallow because it's not something any of us can control. And, if we're being honest, our deepest, darkest fear is that without being able to prevent infidelity, we leave ourselves open to the very real possibility we'll be hurt and betrayed by someone we love. 


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Well, brace yourselves, because when it comes to adultery, here’s what’s really going on:

1. Cheating isn't going anywhere

We all do it (and always have). Despite the moral outrage against infidelity, in every culture across the globe, during every period in recorded history, among every race, and religion, and in every social structure, cheating occurs — and frequently. Fisher says, “Despite our attitude that philandering is immoral, regardless of our sense of guilt when we engage in trysts, despite the risks to family, friends, and livelihood that adultery inevitably entails, we indulge in extramarital affairs with avid regularity.” So, if you think your country, culture, age, gender, or religion is a defense against infidelity, you’re wrong. Cheating is a strong thread that has been painfully woven throughout every aspect of human history.

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2. Both men and women are biologically wired to cheat

This is the part that really freaked me out because instincts wired into our DNA are incredibly hard to override. Fisher’s well-substantiated theory is that “sometime around 4.4 million years ago, our ancestors developed a dual human reproductive strategy: serial monogamy and clandestine adultery.” Research shows that cheating serves an important purpose: It’s part of a clever reproductive strategy nature devised to guarantee that humans keep procreating. 

Yep, I know what you’re thinking (because I thought the exact same thing). The last thing someone wants when having an affair is to get pregnant (or get someone pregnant).  Well, perhaps in today's society that’s the case, but our bodies are still hard-wired with incredibly primal ancient impulses. And "perpetuating the species" is one of them. It seems "sleeping around" offers one hugely significant biological benefit to humans: genetic variety.

RELATED: The Harsh Reason 67% Of Married Women Want To Cheat

3. Monogamy isn’t natural

You’re not going to like hearing this, but it turns out that humans aren’t the only animals on Earth with a wandering eye. Only 3 percent of all mammals form a pair bond to rear their young, and among the few who do, they still get quite a bit of action on the side. When it comes to our modern view of relationships, Fisher reminds us that the word monogamy, when broken down, means "one spouse" (as it relates to pair bonding for child rearing). “It does not mean fidelity.”

@wendyzukerman So many people use cherrypicked science to say whether monogamy is natural or not… here’s the real nerd word #science #sciencetok #monogamy #polyamory #polytiktok #polyamorousrelationship #evolution #primate ♬ original sound - wendyzuk

Monogamy is a social construct. We decided we wanted it around the Agricultural Revolution (for reasons that have far more to do with controlling women, protecting property, and securing bloodlines than “true love”), but fidelity has rarely existed in nature. “We’ve never found a species that’s intimately faithful,” says Fisher. Fidelity is a quaint modern choice, but it is not a primal instinct. Of course, that leads us to an obvious question: Is there any hope for true love and fidelity? Absolutely. Though we’re each wired with a genetic impulse to stray (and plenty of jerks will use that as an excuse for sneaking into bed with someone else), the most distinct hallmark of being human is free will.

We continually evolve as a species (and as individuals) based on the conscious choices we make. And choosing to remain faithful to the partner you love is very much an option. Just don’t stick your head in the sand about the REAL reason people cheat. Don’t foolishly assume your “love” is some magical pixie dust that will override millions of years of evolutionary biology. When it comes to cheating, we make a lot of modern-day excuses for what’s a very deep and primal instinct. As Fisher so eloquently states, “The greatest 21st-century issue in relationships will be how each of us handles these conflicting appetites.” Just remember at all times that fidelity is a choice, not an instinct. If you want your relationship to thrive, let your moral compass on the subject guide you, not your DNA.


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Cris Gladly is a writer, speaker, and connection strategist with a passion for positive human relationships. She writes locally about food, travel, and community; writes nationally about love, relationships, social change, and parenting; and is an independent global consultant helping integrity-centered brands and individuals powerfully transform the way they position themselves and build connections with others.