I'm a fan of neither rap not Eminem, and I confess I don't know much about him other than what I've just read on Wiki. Neither do I have too much time for adults who continue to use their unhappy past as an excuse for their current failings.
But sometimes childhood experiences, even if they're not especially 'bad' bad, can stay with us for most of our lives, even if we don't necessarily hold them responsible for what we are now. They colour everything we are and everything we do and there is something, either in nature or nurture, that will not allow us to let it go.
I wonder if he's maybe seeking the reasons/solutions to his own failings in the actions of his father.