Conservative Fecundity

In today's Wall Street Journal, I learn about the GOP's secret weapon:

According to the 2004 General Social Survey, if you picked 100 unrelated, politically liberal adults at random, you would find that they had, between them, 147 children. If you picked 100 conservatives, you would find 208 kids. That's a "fertility gap" of 41%. Given the fact that about 80% of people with an identifiable party preference grow up to vote the same way as their parents, this gap translates into lots more little Republicans than little Democrats to vote in future elections.