OKCupid has dug into their dataset and has looked at gay sex vs. straight sex. (Safe for work, unless charts aren’t safe for work.) It turns out that at least in their data, men and women are equally promiscuous.
Back in 2007, and in more mainstream data sets, the numbers were different. The numbers seemed to vary from population to population, but one thing was consistent: men reported having had twice as many female sexual partners as women reported having male sexual partners. The obvious explanation, of course, is that people lie about how many sexual partners they’ve had, and that men and women lie in different directions (men adjust their number upwards, women downwards).
But this doesn’t show up in the OKCupid data set: the median number of sexual partners for both straight men and straight women, in their data set, is six. This is also the median number of sexual partners for gay men, and for gay women – OKCupid actually points this out to make the point that gay people are no less or more promiscuous than straight people. If you object to comparing medians, they actually give the whole distribution curve; the distributions of number of sexual partners for OKCupid-using straight people and OKCupid-using gay people are substantially the same. (Not having the raw data, I can’t say if the difference is statistically significant, but who cares?)
Of course this only says something about the self-selecting pool of OKCupid users. But it seemed worth calling out.
God plays dice 
As usual, their statistics posts are food for thought. I found the fact that they had to shrink “The L Word” to fit in the lesbian interest chart vastly amusing.
Regarding men and women’s tally of number of sexual partners, I would think that it would be a very difficult question to answer correctly. It depends on a lot of imprecise definitions. For example, it’s not at all clear to me that sex is even transitive.