From Will Wilkinson, in a 100+ comment discussion at Overcoming Bias:

I would guess that number of children is negatively correlated to number of sexual partners.

According to the General Social Survey, Will’s guess is… correct!  The correlation between number of children and PARTNRS5, its best measure of total number of sexual partners, is -.26. 

This result holds up in a multiple regression that controls for age and the year in which the question was asked:

numkids.jpg

Nice guesswork, Will.

* Note: Here‘s how the GSS codes responses for PARTNRS5.  To make the variable monotonic, I only counted responses from 0-8.