I picked up on Jons' parental clues all on my own from reading the books. This is the first I have ever heard about different parentage for Tyrion, though it makes sense once laid out that way. Could also be nothing. Sometimes I think Martin changes his story just to spite his fans. Seriously.
“Eternity is a terrible thought. I mean, where's it going to end?”
― Tom Stoppard, Rosencrantz and Guildenstern Are Dead
― Tom Stoppard, Rosencrantz and Guildenstern Are Dead