He hates the Flash because he admires his uncle Daniel, who's the Reverse Flash. He comes from a broken home (dad abandoned the family, mom went missing), and the first time we see him in the present, Barry busts him for spray-painting graffiti on a wall. We later find out Iris is his aunt, and she thinks he's a good kid who just needs a strong paternal figure (no real explanation as to why it needs to be a man, as opposed to his successful, intelligent, and well adjusted aunt) to straighten him out.
So, like I said: a mass of stereotypes.