Season 6 finale did give off a major spoiler on Jon’s parentage, when Bran saw his father, Ned, enter the Tower of Joy and saw his aunt Lyanna lying in a pool of blood, having given birth to a son all the while whispering the son’s name to Eddard, which wasn’t heard by Bran; Although the very next scene transitioned to Winterfell, showing us Jon Snow, which clearly hinted us that the son is none other than Jon.
Although, GoT fans have “known” this theory since really long, because Ned isn’t someone who would cheat on his wife, and the only possible explanation was Jon being Lyanna’s child.
Now, a first official spoiler on Season 7, reveals a infographic, that shows 2 parent lines- that begin at Jon, and end at – Lyanna Stark and other at Rhaegar Targaryen.
Now, after this official confirmation, it’s all left to be seen how this affects the game of the Iron Throne, with Jon being the true heir to the throne and Cersei ruling it.