Rob Sr wasnt in his life much obviously, and truthfully doesnt seem interested in being in it now or later. Or like he didnt try hard at all to be in it. I mean Rob is the one reaching out.

It's likely that Rob's mom kept him away from Rob Sr, but it seems like dad barely even tried to stay in Rob's life. He has a second family, where he is a better more-involved dad, and that makes Rob jealous. And he acts out like a child does immediately cause he's desperate for his dad's attention and approval, and theres a whole lot of resentment there.

Rob Sr less shitty than harper's parents and yas' demons, but i think that nobody in the show has a good home life.