"The average heterosexual man has nine sex partners in a lifetime. The average woman has four."
He is talking about statistics, where, for instance, a monogamous couple may have 5,000 experiences over 50 years, but only one partner each.
Or the wife was a monagamous widow whose first virgin husband married her, went off to war after their honeymoon, and was killed. Then she married another virgin young man, and they lived happily monogamous for 50 more years. Each man had an average of one partner, but she has an average of two partners.
Or take the dairy farmer, in the old days before artificial insemination, who has 30 cows and two bulls, one after the other was butchered. Each of the cows were freshened at different times by each of the bulls. So each bull had an average of 30 partners, but each cow had only two partners.
This is statistics, and we are counting the number of different partners, not the number of experiences. Then apply this kind of thinking to a whole population, over a number of years. It merely means that men seem to be more active, on the average, than women.
Is that making sense to you?
If taking the whole population into account, with the assumption that the number of male and female are equal; then the AVERAGE number of sex partners between the sexes must be equal.
Unless you consider masterbation to be hetro sex than there must be one f for every m. And let’s say most women have 4 partners over their lifetime. There will be a couple that have 50 and they have to be averaged into the equation. Thus M and F must be equal. There cannot be hetro sex w/o a woman.