Since the first season of Game of Thrones we believed Jon Snow was Ned Stark's illegitimate son. Before long though theories began flying around, wondering if, actually, Jon could be the child of Lyanna Stark instead, Ned's sister.
In the final episode of season six we finally got to see inside the Tower of Joy, where Ned found his dying sister begging him to "Promise me, Ned", as a newborn baby was thrust into his arms. The next scene confirmed the theory. Jon is Lyanna's child.
But what that episode didn't show us was who Jon's father is - something HBO itself has since decided to clear up.
Rhaegar Targaryen is Jon's father. Jon is fire and ice.
But this all means, as suspected, Daenerys Targaryen is Jon's aunt.
Season seven is going to be ... interesting.