Unless there are a lot of deconversions

I'm expecting a lot of deconversions. Mormons already go to a lot of trouble to retain members and punish former members, which suggests there's a corresponding amount of pressure to leave. Catholics did the whole breed-like-crazy thing, and that worked out well for a while, but catholicism doesn't rule the world.

I think the relative zeal of recent converts as compared to lifelong believers has something to do with how siblings raised apart are more likely to have sexual feelings for each other, but that's probably a topic for another time.