I was recently having a chat with a dear friend of mine, and the number of sexual partners came up. My friend guessed that his number was well below average because he had been in a stable relationship for several years. His number was 6. This got me thinking: What is the average number of sexual partners people have had?
Enter The Health Survey of England--a survey of over 12,000 men and women with this exact question being asked. You can read a Telegraph article all about it here.
The key highlight is that women on average report 4.7 partners and men report 9.3. At first glance, this fits our stereotypes: Men are out there trying to sleep with anything that moves while women are the more chaste of the sexes. But after this initial reaction, we might start to wonder who in the world are all these men sleeping with?
Imagine you have 100 men and 100 women. We will also say that the average man is reporting 10 partners and the average woman is reporting 5 to make our lives a bit easier. So in this case, we are expecting 1000 pairings based on what the men are saying and 500 pairings based on what the women are saying. Where are those extra 500 pairings coming from?
One possibility is sex workers. Its probably reasonable to suspect that sex workers were less likely to take part in the survey, and so perhaps its this group of women who have had a great number of partners that is making up for the gap? Here's the problem with this possibility: At best, 50% of men have to be using sex workers, and at worst, ALL men are using sex workers. Going back to our example, the 500 pairings the women are reporting could completely account for the reported sexual partners of 50 men. That would leave the other 50 men having to get ALL of their sexual partners from sex workers. On the other extreme, lets say each man has 5 non-sex worker partners. Then every man must sleep with 5 sex workers to make up the gap. Both these cases strike me as extremely implausible. Sex workers may explain some of the gap, but likely a small portion of it.
A second possibility is that this number is being driven by gay men, who we do know tend to have greater number of sexual partners than heterosexual men and women, and lesbian women. According to the 2011 UK Census, roughly only 1% of the population reported being gay or lesbian. Lets assume this number is a gross underestimate and the real number is 5%. So lets go to our running example. We need to account for 500 pairings for women and 1000 pairings for men. Lets say 95 of the women and 95 of the men are heterosexual, so they account 475 pairings for each. The 5 lesbian women need to account for 25 pairings, so five a piece there. But the five gay men need to account for 525 pairings! So they would need to each average 105 partners! In our running example, thats impossible--since there are only five gay men--but this isnt a problem if you have a larger population. What is a problem is that 105 partners is a very, very large number--making the gay men explanation also hard to believe. And this is with us assuming that 5% of the population is gay or lesbian. Had we gone with the rate reported (1%), that would require gay men to have on average 505 sexual partners to make the math work!
The third possibility is people are lying. Our societies still sadly have double standards for the men and women when it comes to sex: Women are far more likely to be viewed negatively for having a large number of sexual partners than men. Men may even gain status and prestige from having a high number of partners. And so we have pressure for women to underreport and for men to overreport. In the Health Survey of England, 1/3 of the men admitted to estimating the number of partners they've had. Yea, estimating up.
Sex workers and higher levels of sexual partners among gay men are likely part of the answer (small parts) for the discrepancy, but I'd bet the biggest reason behind the discrepancy is people fudging the truth.
So back to our original question: How many sexual partners have people actually had? Probably somewhere between 6 to 8 (for heterosexual men and women), if we guess that men are overstating it and women are understating it.