Why is infidelity so frequent?

Key Points: Infidelity is widespread, but Americans advocate monogamy. Among other mammal species, only about 9 percent mate for life. This also applies to humans; sexual exclusivity is not innate. Proponents of monogamy say non-monogamy and open relationships don’t work, but maybe it’s time to rethink exclusivity.

Most pegged Americans assume they are calling for monogamy. For many, any violation of sexual exclusivity is a disaster. “He cheated. It’s over. “Even when infidelity doesn’t create a breakup, it often causes severe relationship damage. Therapists see a steady stream of couples trying to record the pieces. Linked people have the right to insist on monogamy, but for many people it is impossible to limit yourself to just one lover for life.

Are humans inherently monogamous?

Many insist that monogamy is “natural”. In fact, only about 9 percent of mammalian species mate for life, and among humans, the prevalence of infidelity defeats claims that sexual exclusivity is innate:

  • Polygamy was common in the Bible – multiple wives or one official wife plus concubines. In Genesis Jacob had two wives, Leah and Rachel, and two concubines, Bilhah and Silpah.
  • The Ten Commandments hold infidelity such a hideous sin that not one but two commandments forbid it: You shall not commit adultery. You shouldn’t covet your neighbour’s wife. Do not do it. Don’t even think about it. If the ancients had been conveniently monogamous, these commandments would have been unnecessary.
  • Mormons were publicly polygamous until 1890. Some still are.
  • There are sex and swing clubs in every metropolitan area and many rural areas – look for “sex and swing clubs” everywhere. The former is usually open to all adults, the latter to couples and single women.

Proponents of strict monogamy often claim that non-monogamy just doesn’t work. For most, this may be true, but I know several happy long-term couples who have occasionally practiced non-monogamy for decades:

  • One, 15 years together, is monogamous, but every year for the woman’s birthday her husband arranges a threesome with another man every year.
  • Another, married for 20 years, is basically monogamous, but every month the woman spends a weekend with her secondary husband.
  • A third, 25 together, maintain monogamy at home, but grant each other permission to play when either of them is on business.
  • A fourth, married for 30 years, meets with secondary lovers every few weeks. The woman explains, “I’m only in love with my husband and he is only in love with me. But we both like to play on the side. It keeps our conjugal sex fresh and exciting. Occasionally we run into one of our secondaries in town. We introduce ourselves, talk a little. Everyone smiles. It’s good.”

If monogamy is natural, then why are so many novels, plays, films, songs, and television shows revolving around its injury? Some observations:

  • “Monogamy is like reading with a 20 watt light bulb. It works, but it’s not enough. “Playwright John Patrick Shanley (1950-).
  • “We drove back to the hotel and said goodbye. How hypocritical it is to leave the man you want to be with for a man you don’t want and then in great excitement have sex with who you don’t want while pretending to be him the one you do. This is monogamy. “Author Erica Jong (1942-), in Fear of Flying (1973).
  • “I told my wife I was going to see a psychiatrist. She told me that she saw a psychiatrist, two plumbers and a bartender. “Comedian Rodney Dangerfield (1921-2004).

Monogamy critic Dan Savage points out that until the 20th century, most cultures assumed that men were not inherently monogamous. Monogamy was only for women, forced by men to control women’s sexuality and guarantee fatherhood. This is still the case in many cultures.

Savage points out that we humans are decidedly imperfect, but when it comes to sexual exclusivity, many demand perfection. “Isn’t it time to rethink monogamy?” he asks. “It’s like sobriety. You can be sober for years, then fall off the cart and sober up again. If couples have been married for 30 years and only get off a few times each time, they are not reprehensible. You’re actually very good at monogamy. “Savage coined the term“ monogamous ”to describe supposedly monogamous couples who accept the occasional mistake.

How common is infidelity?

Infidelity is difficult to research. Few like to admit it. I remember doing a survey that found that only a tiny percentage of married people have ever been lost. The researchers interviewed subjects in the presence of their spouses. Moron!

Admitting non-monogamy depends on how researchers ask the question. Scientists from the University of Colorado surveyed 4,800 married women about infidelity last year. Both personal interviews and an anonymous questionnaire were used. In the interviews only 1 percent admitted, in the anonymous questionnaire 6 percent.

Meanwhile, controversy is tarnishing the definition of “infidelity”. Most say it’s sex with someone other than your partner. But what about spouses who have separated but not divorced? Or couples who have been separated due to an extended military mission? Or involved in don’t-ask-don’t-tell marriages? Is infidelity defined as sex outside of marriage? Or just secret sex? Or just sex with emotional involvement? What about sex with sex workers? Or supposedly straight people who have gay, lesbian affairs? And does cheating require intercourse? What if you just flirt? Or kiss?

A huge research literature has examined infidelity. Some highlights:

  • While one partner at a time is the norm, 84 percent of known human societies throughout history have allowed men to have more than one ongoing sexual relationship.
  • Since Kinsey’s studies in the late 1940s, credible estimates of lifelong infidelity among heterosexual Americans have been widespread – 12 to 72 percent for men and 7 to 54 percent for women.
  • Three-quarters of American adults describe extramarital sex as “always wrong,” but a majority of Americans who have been unfaithful consider themselves justified.
  • Infidelity is associated with: previous cheating; Boredom, dissatisfaction and length of relationship; Expectations of upcoming separations; and poor quality partner sex with low frequency. In men, the risk also increases if partners are pregnant or there are babies in the house.
  • Among the unfaithful spouses, half of the men (56 percent) and a third of the women (34 percent) describe their marriages as “happy”.
  • Infidelity is linked to several personality traits: loneliness, extroversion, anxiety, depression, mood swings, narcissism, openness to new experiences, frequent alcohol consumption, a history of child sexual abuse, and the knowledge that one or both parents were unfaithful. Traits associated with strict monogamy include conscientiousness and regular religious observance.
  • In terms of education, the curve is U-shaped. Those with the lowest and highest levels of education share the greatest likelihood of infidelity.
  • Working outside the home doesn’t make much of a difference. Half of the scammers, both men and women, meet their parameters through work, the other half in other ways.

The Rutgers and SUNY Stony Brook researchers reviewed 148 studies from around the world and concluded: “Despite near-universal disapproval, infidelity is a global phenomenon that occurs with remarkable regularity.”

So widespread infidelity is that some researchers suggest that it is genetic and offers an evolutionary survival benefit. The evolutionary mission of life is to reproduce. The best way for men to do this is to mate with as many women as possible. Over the aeons as early primates evolved into humans, males who mated with most females were more likely to have offspring who may have carried genes that made them philandering.

Is there an evolutionary reason for non-monogamy?

The best way for women to send their genes into the future is to raise children to sexual maturity. It is a challenging task that is made easier with the help of a loyal man. However, researchers speculate that women and their offspring gain a survival benefit by having “surrogate men” who can provide resources when their primary partners die or leave. Women can also use infidelity to “bargain” with partners with more resources. Infidelity women may have had more children – they passed down genes that tended their offspring towards continued infidelity.

The Rutgers-Stony Brook researchers concluded: “Throughout history, infidelity has paid off for both men and women, preserving the genetic basis and today’s taste for infidelity.”

You shouldn’t commit adultery. But evolution may have made us get lost. Civilization is only 10,000 years old, evolutionarily new. More than we’d like to admit, we can still be animals driven by animal instincts.

Despite much research, the true prevalence of infidelity remains a mystery. We just know that it happens so often that we are always sad but not always surprised when we hear about us seducing couples we know.

Facebook picture: Olena Yakobchuk / Shutterstock


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Dan Savage on monogamy: https://www.youtube.com/watch?v=w8SOQEitsJI

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Treas, J. and D. Giesen. “Sexual Infidelity Among Married and Cohabiting Americans,” Journal of Marriage and the Family (2000) 62:48.

Whisman, M. et al. “Predicting Sexual Infidelity in a Population-Based Sample of Married Individuals”, Journal of Family Psychology (2007) 21: 320.

Whisman, MA and DK Snyder. “Sexual Infidelity in a National Sample of American Women: Differences in Prevalence and Correlates as a Function of Scoring Method,” Journal of Family Psychology (2007) 21: 147.

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