Why Men Cheat

To be honest, both men and women cheat. But that said, men are more likely than women to cheat and there are some differences between the sexes when it comes to cheating.

In order to understand why men cheat, it helps to understand what causes both men and women to be unfaithful.

Why do both men and women cheat?

The science of cheating is clear on this point: Roughly 3% of all mammals, including humans, practice what is called pair bonding or monogamous mating. However, even within the 3% of mammals that practice monogamy, very few species, including humans, are truly monogamous (see Barash & Lipton). In fact, when it comes to both men and women, monogamy is not our natural sexual strategy (see Barash & Lipton; Ryan & Jetha).

To make a long story short, for millions of years the desire to mate with multiple partners was a useful reproductive strategy. Men and women who had multiple partners likely produced more offspring than people who were faithful to a single mate. Cheating was a strategy to increase reproductive success and diversify risk. Or think about it in this way: investing in a mutual fund (multiple stocks) is, on average, a better financial strategy than putting all of your resources into a single stock.

Because a multiple-partner approach was a better reproductive strategy than monogamy, men and women living today are the descendants of people who had the desire to have sex with more than one other person over the course of their lifespan. Simply put, we have inherited this trait from our ancestors—it is a part of our human nature. This does not mean that everyone will cheat on a partner, or that people are fully aware of their unconscious sexual desires. For a more detailed discussion on the nature of cheating, please see why people cheat.

How are men and women different when it comes to cheating?

While both men and women cheat, there are important sex differences when it comes to cheating. The sex differences that influence cheating are based on two basic biological differences between men and women

First, men and women differ when it comes to reproductive biology. Men can produce hundreds of millions of sperm per day. By comparison, women are born with a million or so eggs, of which only a fraction, roughly one egg released every 28 days during the years of puberty to menopause—has the potential to create life. Simply stated, a woman has about 400 viable eggs to use (but taking into account gestation, she can become pregnant only about 20 times), while men are capable of fathering an unlimited number of children.

The second basic biological difference deals with gestation. Embryos grow and develop in women, not men. For men, reproduction can literally take just a few minutes of effort, while for women it involves a nine-month process.

From a biological point of view, men can quickly and repeatedly engage in reproduction while women are much more limited in their ability to do so (see why women cheat).

These biological differences influenced our psychological desires before the invention of modern forms of birth control and still influence our sexual desires today. Men are more likely than women to think about sex and fantasize about having sex with multiple partners (take our indecent thoughts survey). In fact, a multi-billion dollar industry—pornography—exploits this basic sexual difference.

Given this basic biological difference, here are some key differences between men and women when it comes to cheating:

  • Men are more likely than women to cheat with someone who is less attractive than their current partner. Women cheat up while men are more opportunistic when it comes to cheating.
  • Men are more likely than women to have a one-night stand. Women are more prone to having emotional affairs.
  • Men are less likely to consider leaving their partners after cheating. When women cheat, there tends to be more emotionally involvement, so they are more likely to consider ending their current relationship.
  • Men are more likely than women to repeatedly cheat on a spouse or partner (see for example, my husband constantly cheats).

For more information on cheating and infidelity, we have put together the following resources:

Truth About Deception – back to our home page.

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