The Kingship Passes Through the Royal Women

To become a true pharaoh of egypt, you had to marry the heiress who carried this kingship within her. So if you were born the son of a king, you would marry your sister. But we now know that this theory is not true, because we have pharaohs who didn't marry their sisters and they were perfectly successful pharaohs. It's something that's made people feel uncomfortable for a very long time. Whereas to the egyptians, it was just what they did, i guess, part of life.