Every high school club wants to be the cool one

From a New Yorker article on high pregnancy rates among evangelicals:

Bearman and Brückner have also identified a peculiar dilemma: in some schools, if too many teens pledge, the effort basically collapses. Pledgers apparently gather strength from the sense that they are an embattled minority; once their numbers exceed thirty per cent, and proclaimed chastity becomes the norm, that special identity is lost. With such a fragile formula, it’s hard to imagine how educators can ever get it right: once the self-proclaimed virgin clique hits the thirty-one-per-cent mark, suddenly it’s Sodom and Gomorrah.