[apillar]

Actually, half-brother / half-sister marriage was the norm among Egyptian royalty for thousands of years. Genetically it only became a problem after occurring over multiple generations. Our modern aversion to close relation marriage is more based on cultural taboos than any real science. For much of history (and in many parts of the world still today) such marriages were common.

[yldstrk]

I think it is based on God and the Bible apillar. Who gives a spit about “science” of ethics? Get real.

[donmeaker]

Half sibling is about the same as first cousin, which is legal in CA, NY, and NM, among other states.

British royal families did a bunch of cousin marriages, back in the day, and although a bit funny looking, they are still around.