The business about Jon Snow being the son of Rheagar and Lyanna is speculation. Widely believed speculation, but speculation nonetheless. Martin has not yet revealed Jon's parentage.
[Edit--if you're curious why people speculate that this is the case, it looks like this page sums it up nicely.
[ January 30, 2007, 04:11 PM: Message edited by: Noemon ]
Posted by Uprooted (Member # 8353) on :
Thanks, Noemon! I actually wondered if it was really revealed or just speculation . . . somehow it had that ring of "I shoulda thought of that!" as soon as I read it.
I'm just being stubborn about reading A Feast for Crows because when I heard about the format I decided it would drive me nuts waiting till the next book came out, and that I'd just wait and read them both at the same time.