Jon and Daenerys both grew up outcasts and had to fight harder than most for even the smallest amount of respect and power.
Jaime and Cersei began their twisted love affair when they were children — children who probably should have known better, but ultimately children nonetheless.
Jon still has no clue of his true heritage, and he likely won’t learn it for quite some time.
As Bran’s vision of the Tower of Joy in Season 6 confirmed, Jon isn’t the bastard son of Ned Stark (Sean Bean).