The OP is extraordinarily qualified academically, and should approach college from that standpoint. I knew teetotallers and people who never smoked pot, even back in the wicked, wicked 1970s. I think you’re likelier to find a straitlaced population in the sciences than elsewhere. Students in those fields are very competitive academically, and often come from conservative (in the “lower-case,” social sense of the word, if not in terms of political affinities) backgrounds. If he cares more about an abstemious student body than about academic reputation, then he should focus on religious-affiliated colleges like BYU, but he should have no trouble finding like-minded students at MIT, CalTech, Washington U, Harvey Mudd, Columbia SEAS, Olin, et al.