Ippo is the son of a fisherman. If Hajime no Ippo were a modern shonen he would Mike Tyson's secret japanese son and the long lost descendant of Sugar Ray Robinson and the Marquess of Queensberry.

Also there is nothing wrong with a character being a prodigy or from a special bloodline. It's only bullshit when the story starts out by portraying them as just a regular person then decides that they need to be magic anime jesus in the middle of the story.