The mystery of Snow's parentage has been one of the most enduring mysteries-not just in the show, but also in the original books by George R.R. Martin. Theory after theory has circulated, the most popular being "R+L=J"-or, put in plain English:
Rhaegar Targaryen + Lyanna Stark = Jon Snow
Fans finally got some clarity in the season-six finale, "The Winds of Winter," in which Bran Stark uses his powers to glimpse the truth: Snow's mother is indeed Lyanna Stark. The pivotal scene shows Snow's birth by Lyanna, the late sister of Ned Stark, who of course then wound up raising the "bastard" Snow. It's a riveting moment, and it prompted massive sighs of relief among die-hard fans as they took in this confirmed reality.
While the identity of Snow's father was left slightly unclear, an infographic from HBO basically gave it away. The family tree shows Snow's connections to Both Lyanna and Rhaegar Targaryen.
Then, in season seven, Bran went ahead and confirmed what everyone was thinking when Jon Snow and Daenerys Targaryen had sex: They're technically nephew and aunt. Game of Thrones keeps it casual like that.