Research shows women may be cheating now almost as much as men. What are the tolls of new temptations?
Some 60 years ago, Alfred Kinsey delivered a shock to mid century sexual sensibilities when he reported that at some point in their marriages, half of the men and a quarter of the women in the U.S. had an extramarital affair. No one puts much stock in Dr. Kinsey's high numbers any more -- his sampling methods suffered from a raging case of selection bias -- but his results fit the long-standing assumption that men are much more likely to cheat than women.
Lately, however, researchers have been raising doubts about this view: They believe that the incidence of unfaithfulness among wives may be approaching that of husbands. The lasting costs of these betrayals will be familiar to the many Americans who have experienced divorce as spouses or children.
Among the most reliable studies on this issue is the General Social Survey, sponsored by the National Science Foundation, which has been asking Americans the same questions since 1972. In the 2010 survey, 19 percent of men said that they had been unfaithful at some point during their marriages, down from 21 percent in 1991. Women who reported having an affair increased from 11 percent in 1991 to 14 percent in 2010.
A 2011 study conducted by Indiana University, the Kinsey Institute and the University of Guelph found much less of a divide: 23 percent for men and 19 percent for women. Such numbers suggest the disappearance of the infidelity gender gap, but some caution is in order.
An enduring problem for researchers -- even those who sample with meticulous care -- is that any such survey is asking for confessions from people who are presumably lying to their spouses. Researchers generally believe that actual infidelity numbers are higher than the results indicate.
It should also be emphasized that cheating in the U.S. isn't epidemic or inevitable, for either sex. Surveys consistently find that by far the majority of respondents value monogamy and think that infidelity is harmful. And if you believe the General Social Survey's finding that 14 percent of women are cheating, keep in mind that 86 percent aren't.
Still, even though survey accuracy is difficult to achieve and experts are by no means unanimous, it would appear that women are, indeed, catching up. In my own work as a psychologist and in my social circle, I see more women not only having affairs but actively seeking them out. Their reasons are familiar: validation of their attractiveness, emotional connection, appreciation, ego -- not to mention the thrill of a shiny new relationship, unburdened by the long slog through the realities of coupledom.
Researchers also point to other factors that might be leading women to stray more. One is what might be called "infidelity overload." Scan the plots on any given week in television, and there seems to be more extramarital sex than marital sex. (Few spouses stay put in Mad Men.) With women portrayed as eager participants and aggressive instigators, there may be a feeling that infidelity has become more acceptable.
And then there is the opportunity factor -- more travel, more late nights on the job and more interaction with men mean that the chances and temptations to stray have multiplied for the new generation of working women.
A 2011 study at Tilburg University in the Netherlands, published in the journal Psychological Science, argues that infidelity is also a function of greater economic and social power, which creates confidence and personal leverage for both genders. Women can now use their power in ways to which men have long been accustomed.
A broader cultural shift may also be at work. According to a Match.com study conducted earlier this year by the biological anthropologist Helen Fisher, women are becoming less traditional about relationships. Men, interestingly, may be going the other direction. In the survey, 77 percent of women in a committed relationship said they needed personal space, as opposed to 58 percent of men. While 35 percent of women wanted regular nights out with friends, only 23 percent of men said the same.
Social networks are another factor, if only by expanding the pool of possible partners. Emotional friendships that turn physical are the traditional point of entry for female affairs. It is now easy for those friendships to take root online. Some argue that social networks are merely an expediter and that cheaters will always find a way. Still, if you've never quite gotten over your prom date, today the chances are much better that you can find him.
Do women account for more of today's affairs? Probably. But in a society that has been preaching, legislating and celebrating gender equality for decades, equality in marital misdeeds might be expected too.
Dr. Drexler is an assistant professor of psychology in psychiatry at Weill Cornell Medical College and author, most recently, of "Our Fathers, Ourselves: Daughters, Fathers and the Changing American Family."
This appeared on wsj.com. A version of this article appeared October 20, 2012, on page C3 in the U.S. edition of The Wall Street Journal, with the headline: "The New Face of Infidelity."