It's not as simple as having a "anti-abortion gene" or not, but there are some really interesting studies about this:

> A 2005 twin study examined the attitudes regarding 28 different political issues such as capitalism, unions, X-rated movies, abortion, school prayer, divorce, property taxes, and the draft. [...] Genetic factors accounted for 53% of the variance of an overall score.

(https://en.wikipedia.org/wiki/Biology_and_political_orientat... - linking to Wikipedia because it has some links)