@Tfmonkey "There's nothing in the Bible that condemns incest."
Are you for real? Leviticus 18 goes over this extensively. It does not prohibit sexual relations/marriage between cousins, so that might be a point of contention. But to say there is no condemnation of incest is just wrong.
I will not defend the whole situation with Lot and his daughters. It does not condemn or condone what happened, but rather just says that it happened.
Not only does the Bible forbid incest between biological relatives but it sonetimes forbids incest between people who are not even close biological relatives for example in the Olld Testament it is forbidden to marry a adult woman and her adult daughter
But if the adult woman is a widow then the man marrying both of them might no be a close biological relative of either one
This rule makes no sense to prevent birth defects in any way that I can think of