Incest

[Beest]

Originally Posted by Aliantha

Well personally, the risk of a child being born with not enough chromosones etc is probably the main reason why I think it should be avoided.

Good point, potential harm to a third, innocent, party.
But.... smoking and drinking while pregnant aren't actually illegal, but should be avoided.
I'm trying to think if someone has been charged for abuse of a minor for smoking/drinking while pregnant and causing abnormalities, i don't remember an instance, but it wouldn't surprise me in the least.