I think [Douthat's] larger point is accurate: it's really difficult to change the sexual habits of adolescents.
That's because we've been trying to change behavior with facts and information. We've assumed that the way to get kids to wear condoms is give them statistics about sexually transmitted disease, or that the way to get students to abstain from sex is to lecture them on morality, or the difficulty of caring for a child while in high school. The problem with such facts is that they don't help teens deal with their moment of sexual decision, which most likely occurs when they're half naked and deranged with desire. In other words, we've assumed that sexual choices are rational choices, influenced by classroom exhortations and dry information. But that's wrong.