More gender politics: it's about whether you have sons or daughters.

You've heard the idea that Democrats are the Mommy Party and Republicans are the Daddy Party. And you know they say that women tend to be liberal and men conservative, the "gender gap." Here's the theory that leaning left or right has something to do with whether you have daughters or sons:

In Germany, two-thirds of people who switched their political affiliation in the year after having a son moved to the more conservative party. The ratio was flipped for those who had a daughter.

In Britain, the two left of center parties, Labor and the Liberal Democrats, do much better — 11 percentage points — among voters with three girls and no boys than among voters with three boys and no girls....

In small ways, having a daughter seems to make men think a little bit more like women when it comes to economic considerations like health care — and to make women focus even more on those issues. Democrats pushed for the Family and Medical Leave Act over Republican objections, for example, and more voters agree with Democratic positions on health care.

"You see a different set of experiences" when you have a daughter, said Celinda Lake, a Democratic pollster. "You tend to see more of a role for government and more of a need for a safety net."

But the findings cut both ways. Boys aren't neutral. They seem to make some parents more conservative. In the United States, just 31 percent of parents with only boys call themselves Democrats, while 37 percent with only girls do, according to the General Social Survey, a large poll.

One reason, Mr. Oswald said, might be that men work longer hours and earn more money than women, giving the parents of boys reason to want lower taxes. Men also tend to prefer that individuals make decisions, a view that fits with Republican beliefs, while women prefer community solutions.

One more reason to say Althouse is right wing: I have sons.