Do Men and Women Have the Same Average Number of Lifetime Partners?

It is generally thought that for sake of consistency men and women must have the same average number of lifetime partners. However, this is not the case in general. When men have younger partners, women enter sexual relationships more quickly than men and have a higher number of lifetime partners. A male dominant model applied to UK data on the male rate of entry into a sexual relationship and the male partnership formation function shows that in a stationary population (zero growth rate) women have 9.1% more partners than men. In a stable population with an intrinsic growth rate of 2% and a larger but still plausible difference between the ages of partners, women have 24.6% more partners than men. Given that in sex surveys men report more partners than women, the resulting bias in estimated numbers of partners may therefore be larger than previously thought