Sorry I find it difficult to respect marriage for a group of people where there is a 50/50 chance they might molest their or your own children. They’ll scream to high heaven that’s not the case but that’s pretty much the odds if a child of the same sex is left with them alone.
It’s not even a question of direct molestation. Would exposing your child to sexually explicit material be considered abuse? I have a suspicion that what I just mentioned is more common. Or how about not helping your child know about what proper relationships are? That’s negligence.