The story goes that before George R.R. Martin agreed to give over the rights to A Song of Ice and Fire, he made current Game of Thrones showrunners David Benioff and Dan Weiss guess what was up with Jon Snow's mom. Now, we don't know what they said, and Kit Harington, the actor who plays Snow, doesn't either, but there is a dominant theory: R+L=J. (From here on forward there are spoilers. Well, kind of. It depends on if the theory proves correct.) The theory posits that Jon's mom is Lyanna Stark, Ned's sister. Before you your brain goes down the incest road, the theory continues that Jon's real father is Rhaeger Targaryen. To understand the reasoning behind this and what this actually means for the show, we present a handy little video. Watch below. Otherwise, you know nothing.