Have you ever wondered how your boyfriend or guy friends seem to always have more sexual encounters than you? Well, you may finally have the answer now and it may be something you have suspected all along.

A new study in The Journal of Sex Research finds that the huge 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. To put in simply, they lie. 

The study also revealed that men tend to estimate rather than count their lifetime total. That, coupled with gender differences in attitudes towards casual sex, explains roughly two-thirds of the notorious 'gender gap' found in many sex surveys.

Dr Kirstin Mitchell of the University of Glasgow and colleagues analyzed the responses of over 15,000 men and women, aged between16-74 in the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3). Their study sought 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 survey, men reported an average of 14    partners in a lifetime while women reported only 7.

Firstly, 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.

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."