Originally Posted by The Imp
Everyone knows that Bran is the younger brother that Maggie The Frog sees in her prophecy
It is not known. What is known is that Cersei thinks the Valonqar is Tyrion. If the Valonqar is Jon, then my crackpot ideas are right and Aerys fathered almost as many bastards as Robert. Uh, but I think the leading (and possibly only) candidates are Tyrion and Jaime.