I posted on here once that I take a view of creation that God created many people outside of Adam and Eve because of one of their sons leaving to meet his wife and because the Bible never says that God created only Adam and Eve. Another poster mentioned that it was possible for brother and sister to mate, or even parents to offspring, if they had perfect genetics with no abnormalities and that I "didn't understand how it works." I never got back to address the point, so I will now; The reason there would be abnormalities in such matings of humans is because there would be too many base pairs in the genetics sequence that didn't match up with their analogous base pairs. For example you would have too many cases of where cytosine would match up with another cytosine because the mating pair would have too much genetics in common, not because they had abnormalities. Don't get me wrong, I believe in God and Christ etc, but this would not work. Most likely the bible mentions Adam and Eve as either a parable or it leaves out the other people that God created around that time.