Like father like son. Kinda strange that Julian had to go through lost, "unloving" parents the same way John did. John's dad "dissapeared", and his mom (his musical influence) was hardly around, then established a relationship, and was untimely killed. Same thing went for Julian. his dad (in the 60's) disappeared for long periods of time. and in his teens, his musical influence was untimely killed when they were starting to build a relationship.
What doesn't add up is Julian's hostility. I don't know if john was still angry at his parents by the time he died, but Julian is pretty old you'd think he'd let go by now. I'm sure he has (except for the whole "Business" part with Yoko where I'm sure he's tied up in knots--just like paul)