couple in bed

When a man has heterosex, a woman does, too. How could reported frequencies be so different?

Ever since the late 1940s when Alfred Kinsey conducted the first scientific survey of American sexuality, three odd findings have been confirmed over and over again. Compared with women, men consistently report:

• More sex partners.
• More sex with them.
• And more fellatio received and cunnilingus provided.

How could this be? Every time a man has heterosex, a women does, too, so each gender’s number of partners and amount and type of sex should be roughly equal. But they’re not—not by a long shot.

The Numbers Don’t Add Up

University of Alberta, Canada, reviewed the substantial literature on men’s and women’s lifetime number of sex partners. Men said 12. Women said four. So on average, men report three times as many partners as women.

Indiana University and University of Chicago researchers asked a representative sample of more than 6,000 adults about sex during the previous six months:

Those saying “I had partner sex” by age group:

Men            Women

25-44:         92%            90%
55-64:         85%            62%
65-74:         56%            38%
65-85:         39%            23%

In every age group, men reported more partner sex.

In another study, the Indiana group asked a representative sample of 5,865 Americans men and women about oral sex during the past year.

Men Saying Oral received         Women Saying Oral provided

18-39:         68%                                       62%
40-49:         62%                                       57%
50-59:         49%                                       44%
60-69:         38%                                       34%
70+:            19%                                       24%

Women Saying Oral received    Men Saying Oral provided

18-39:         65%                                      67%
40-49:         52%                                       53%
50-59:         34%                                       36%
60-69:         25%                                       23%
70+:              8%                                        7%

Again, in most age groups, men report receiving somewhat more oral than women say they provided, and men report providing a bit more oral than women say they received.

Number of Partners:  Women Enumerate, Men Estimate

Men report more lifetime sex partners apparently because the genders differ in how they come up with their estimates.

The University of Alberta researchers asked 1,787 college students to estimate their lifetime number of sex partners and how they came up with their number. Compared with the men, the women were considerably more likely to enumerate, that is, count up their partners name by name. Some women said they kept running tallies, for example: “I keep a diary, and I know my current boyfriend is #6.” But most recalled their partners from memory.

Enumeration is notorious for producing low estimates because memory plays tricks. People tend not to recall lovers with whom they disliked sex, or had forgettable one-night stands, or sex under the influence of drugs or alcohol.

Meanwhile, the men were considerably more likely to base their estimates on rough approximations. Their comments expressed substantially more uncertainty than the women. Many said they “just guessed.” Some came up with formulas: “Two to three a year for six years.” Men feel social pressure to have sex with many women, so it’s likely that their estimates would overstate their number of partners.

Encounters That Don’t Get Counted

One reason why men report more sex than women is that on average, women live longer than men. As later life unfolds, women increasingly outnumber men. As a result, older men have an easier time finding partners and have more sex, while older women have more difficulty attracting lovers and have less.

In addition, on average, men are lustier than women and pursue sex more avidly. Men like to think of themselves as studs, so at every age, they tend to over-estimate the number of women they bed. Meanwhile, most women view too-frequent sex (whatever that may be) as slutty, a label they’d rather avoid, so they tend to under-estimate how often they’re sexual.

Finally, many men patronize sex workers. The research is limited, but every year, an estimated 16 percent of male Americans—some 20 million men, both single and partnered—pay for sex. Meanwhile, researchers estimate that women who work in what’s often called “the oldest profession” number a fraction of 1 percent of the adult female population, around 1 million. Sex workers are an elusive group, difficult to survey or interview. As a result, their large numbers of sexual encounters don’t get counted, which reduces women’s overall amount of sex.

Men’s visits to sex workers may also help explain why men say they receive more fellatio and provide more cunnilingus than women say they provide and receive.

Did I miss anything? Are there other explanations why the genders differ on reported amounts of sex?




Brown, N.R. and R.C. Sinclair. “Estimating Number of Lifetime Sex Partners: Men and Women Do It Differently,” Journal of Sex Research (1999) 36:292.

Laumann, EO et al. The Social Organization of Sexuality: Sexual Practices in the United States (1994) Chicago University Press, page 82.

Lindau, ST and N Gavrilova. “Sex, Health, and Years of Sexually Active Life Gained Due to Good Health: Evidence from Two U.S. Populations-Based Cross-Sectional Surveys of Ageing,” BMJ (2010) 340:c810.

Herbenick, D. et al. “Sexual Behavior in the United States: Results from a National Probability Sample of Men and Women Ages 14-94,” Journal of Sexual Medicine (2010)  7(Suppl 5):255.

Westerhoff, N. “Why Do Men Buy Sex?” Scientific American Oct. 2012.

“How Many Prostitutes Are Three In the United States and the Rest of the World?”

“Prostitution in the United States.”


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