It is a well known fact that in ancient Egypt, it was not unknown for a Pharaoh to marry his own sister.
As such, I have 2 questions (about pre-Alexander/Ptolemaic times):
How common/uncommon was such a marriage for Pharaohs?
Was the same lax attitude extended to non-Pharaohs, especially "normal" people? Or were they prohibited from sibling marriage like a vast majority of other societies, not being "gods"?