You're right, Cherjcd. This is one of their goofiest and thorniest doctrines.
BTW, there WILL be sex/marriage for the Great Crowd according to the WTS, because technically they're the ones who (according to Revelation) pass through the tribulation into the paradise.
HOWEVER, the other sheep (which equals the great crowd + resurrected ones) are divided into the sexless (resurrected) and childrearing (made it through Armageddon) classes in the New Order. (That is, until God stops procreation, if he doesn't send humans to populate other planets, bla bla bla).
It's all Bible-based, as another poster reminds us.