Andrew at Five Thirty Eight brings us this:
In remarkable research, the sociologist Rebecca Warner and the economist Ebonya Washington have shown that the gender of a person's children seems to influence the attitudes and actions of the parent.
Warner (1991) and Warner and Steel (1999) study American and Canadian mothers and fathers. The authors' key finding is that support for policies designed to address gender equity is greater among parents with daughters. This result emerges particularly strongly for fathers.
I was always told that when I got married and had kids, I would become more conservative. Instead, I've actually become more liberal since meeting my wife and having a daughter. The causality never occurred to me, and I can't pinpoint exactly whether or not it's coincidence, but come to think of it: every Dad I know who has a daughter is, by in large, more liberal. Socially, at least.