A reader submitted the following question:

"Just how common is cheating? What percentage of people admit that they have done it before?"

This is a surprisingly difficult question to answer because it depends upon how you define “cheating.” Specifically, are you talking only about sexual infidelity, or are you also asking about emotional infidelity? When researchers use different definitions, they obtain wildly different results. For instance, in a 2010 review of 31 different studies of infidelity published in the journal Personality & Individual Differences, researchers found that rates of infidelity ranged anywhere from 1.2% to 85.5% of respondents [1]! Typically, studies that define infidelity narrowly (i.e., only in sexual terms) report lower rates, whereas those that adopt broader definitions (i.e., sexual and emotional infidelity) report much higher rates. Indeed, that 85.5% figure comes from a study that used a very broad definition of cheating that even included flirting with someone other than your partner.

Rates of infidelity also vary across certain demographic characteristics and relationship types. For instance, research finds that cheating tends to be more frequent among men than it is among women (although this gender difference has narrowed considerably in recent years). Likewise, infidelity tends to be more common among couples who are dating compared to those who are married. I should also mention that rates of infidelity vary depending upon whether the question is framed specifically in terms of one's current relationship or in terms of whether one has ever done it (obviously, the latter tends to yield higher numbers).

With that said, here are a few statistics you might be interested in. First, let's look at the percentage of married people who say they have ever had sex outside of their current relationship. Looking across the studies included in the 2010 review paper, that number pretty reliably falls between 1 in 4 and 1 in 5, at least among samples collected in the United States (rates of infidelity can vary substantially across countries). Second, let's look at how many college students have ever committed sexual infidelity. Again, the studies reported in this review paper pretty consistently put that number between 1 in 2 and 1 in 3.

Of course, keep in mind that, if anything, these numbers probably underestimate the true prevalence of cheating because not everyone who has done it is willing to admit to it, even on anonymous surveys.

In short, cheating is a very common activity; however, the prevalence of infidelity varies dramatically depending upon how you ask the question and to whom.

For more information on cheating, including some of the reasons people do it and the outcomes associated with it, see here.

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[1] Luo, A., Cartun, M. A., & Snider, A. G. (2010). Assessing extradyadic behavior: A review, a new measure, and two new models. Personality and Individual Differences, 49, 155-163.

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