Lyanna and Padme died in childbirth.
Ser Wun Wun, on 06 June 2012 - 05:18 PM, said:
LOL, since when does GRRM do PG stuff like that? Dany and Jon are guaranteed to screw and
then find out they are related.
Not that Dany will care, but Jon might blind himself ala Oedipus

LOL!
Ygritte had a convo with him about incest before.
Quote
“She punched him, “That’s vile. Would you bed your sister?” “Longspear’s not your brother.” “He’s of my village. You know nothing, Jon Snow. A true man steals a woman from afar, t’strengthen the clan. Women who bed brothers or fathers or clan kin offend the gods, and are cursed with weak and sickly children. Even monsters.” “Craster weds his daughters,” Jon pointed. She punched him again. “Craster’s more your kind than ours. His father was a crow who stole a woman out of Whitetree village…”
I think a "normal" person when asked if they would sleep with their sister would automatically say something along the lines of hell no. It should be like a reflex.
Anyways, I think this comparison is not dead on but there are some parallels. His reaction depends on if Lyanna was willing or not. At this stage he doesn't dislike Targaryens. His hero is Daeron I and he liked Aemon the Dragonknight and Maester Aemon.
It would also be cool to know that the legendary Arthur Dayne died for him. Jon is lucky I like him or else I would deem him unworthy of this honor.