"Republican and Democratic dads have the same number of children, an average of 2.4, and on average they start their families at the same age — 28. They are also equally likely to be employed. In other words, the demographic data tells a story of very similar fathers in the two parties."
From this Post article describing a study of fathers and their attitudes and party affiliations. Otherwise the differences between the groups are about what you'd expect, Republicans more authoritarian, Democrats more self-accusing--in other words the studs versus the wimps.