I started having sex when I was seventeen, with another seventeen-year old. We were smart enough to use birth control. Our parents didn’t know and we sure did what we could to keep them from knowing. In our part of the country we were probably a little older than average. Girls started leaving school because they were pregnant around fourteen, with a peak around sixteen or seventeen. We lived in the Bible belt, by the way. There was one religious group that had a particularly high teen pregnancy rate, and they were so evangelical that they forbade dancing. Vertical dancing, anyway. My point is that as a species we are ready for sex by sometime in the mid-teens; and many societies allow marriage at that age. Our society has decided that people shouldn’t get married until years after they have become sexually mature. Thus the conflict between biology and social norms. Teen-agers are going to have sex. That’s just the truth. We have two choices — let them get married as soon as they are ready to have sex, or help them not get pregnant until they are ready to get married. I vote for the second.