It's obvious that George RR Martin has gathered his inspiration for Game of Thrones from (among other things) mythology. Dragons, for example. But also the common incest. I am right now watching a documentary series about Egypt's forgotten queens, and they are talking about the Myth of Isis and Osiris. Isis is the lead godess in Egyptian mythology, and she was the sister/wife of Osiris and mother of his child. Their brother Seth, synonymus with the sterile desert, killed his brother Osiris, synonymus with the fertile Nile. Jaime/Cercei much?