London School of Hygiene & Tropical Medicine

The disparity between the number of sexual partners reported by men and women can largely be explained by a tendency among men to report extreme numbers of partners, and to estimate rather than count their lifetime total, according to a new study in The Journal of Sex Research.

Together with gender differences in attitudes towards casual sex, this explains roughly two-thirds of the notorious ‘gender gap’ found in many sex surveys.

The findings come from the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) - the largest scientific study of sexual health lifestyles in Britain - carried out by the London School of Hygiene & Tropical Medicine (LSHTM), UCL and NatCen Social Research.

The study team was led by Dr Kirstin Mitchell of the University of Glasgow and the data analysed in this paper were from a study led by Professor Kaye Wellings from LSHTM. The research team analysed the responses of more than 15,000 men and women to better understand why men always report more opposite-sex partners on average than women, even though the average number reported by men and women should be about the same. In the Natsal-3 survey men reported an average of 14 lifetime partners while women reported only seven (participant age range, 16-74).

Individuals who reported very high numbers of partners skewed the average, and this effect was stronger for men than women. Men and women at the top end (99th percentile) reported 110 and 50 or more partners respectively. Excluding these men and women reduced the overall average, closing the gender gap.

The gap reduced further when ‘accounting strategy’ was taken into consideration. Men were more likely than women to estimate rather than count their lifetime partners. For example, among those reporting 5-9 partners, 24% of men estimated compared with 15% of women.

Sexual attitudes also had an impact on reporting. Women were generally more conservative in their sexual attitudes than men. They were less likely than men to view one-night stands as ‘not wrong at all’ (9% versus 18%) and they were more likely to view a ‘married person having sexual relations with someone other than his or her partner’ as ‘always wrong’ (65% versus 57%). Adjusting for these attitudes narrowed the gap even further.

The researchers investigated a number of other explanations. They found that excluding paid-for partners made only a small difference to the gender gap, but gender differences in reported non-UK resident sexual partners had a modest impact over a 5-year period and could also be a potential explanation over the lifetime.

Study co-author Professor Kaye Wellings from the London School of Hygiene & Tropical Medicine, said: “In a given population the number of opposite sex partners in a lifetime should, statistically, be the same for both sexes, so it has long been a puzzle that men report higher numbers than women. We’ve unravelled some of the reasons for this here - crucially, the tendency for men and women to estimate differently, possibly reflecting the so-called ‘double standard’ in social expectations.

With greater sexual equality and softening social attitudes, we’re gradually seeing a lessening of this effect. We’ll then able to understand sexual health needs better and also make more accurate predictions of how far and how fast sexually transmitted diseases might spread.”

Dr Mitchell said: “Accurate reporting of sexual partners is crucial for many reasons, including assessing individual risk of sexually transmitted infections (STIs) and estimating the rate of STI/HIV transmission. Most existing studies of reporting bias are limited to students or high-risk populations, or are conducted as ‘laboratory’ settings, so they don’t show how members of the public respond in a ‘real-life’ survey. To our knowledge, our study is the first attempt to look at all the key types of explanation for the gender discrepancy within the same large and representative sample.”

Publication

Kirstin R. Mitchell, Catherine H. Mercer, Philip Prah, Soazig Clifton, Clare Tanton, Kaye Wellings & Andrew Copas. Why Do Men Report More Opposite-Sex Sexual Partners Than Women? Analysis of the Gender Discrepancy in a British National Probability Survey. The Journal of Sex Research. DOI: 10.1080/00224499.2018.1481193