Forman father/son relationships, by generation (Red and Eric will be a separate one)
Gen 1: Patrick (1848-1878)/John (1876-1968). There's not much of a father/son relationship, because Patrick died in a workplace accident when John was really young. He fiercely loved and protected his son when he was around, though.
Gen 2: John (1876-1968)/Albert (1898-1963). Ouch, but it's mostly Albert's fault. John's a loving father, but he's not too good at expressing his emotions, and sometimes comes off as a bit cold.
John is a more analytical, bookish version of Eric, more or less. He's an awkward bookish type who owns a bookstore and has some progressive (and well, frankly, socialist) views, whereas Albert is far more nationalistic and traditional. And as a result, they butt heads. Hard.
So when John bad mouths the merits of WWI, Albert literally turns him in (look up the Sedition Act of 1918 for more details). And John rots in jail for a little while, which basically estranges them (obviously). John is still in Albert's life, mostly for the sake of the grandkids, but it's insanely awkward, to say the least.
John and Albert get into some intense verbal altercations, ones Red distinctly remembers. As he desperately hopes to avoid the same fate with Eric (but with opposite political views bestowed on father [traditional] and son [more liberal]). Honestly, if Eric was a decade older, I think Red and Eric would have more of a hostile relationship, since Eric would conscientiously object to Vietnam and create a considerable wedge between them.
Anyway, back to John and Albert. At some point, Albert attempts some half-assed olive branch and names his first son John after him (Jerry), but that doesn't accomplish much of anything. They can't stand each other, and that's that.
PS: John outlives Albert by a few years, enough to influence Eric in a way that kind of pisses Red off (because John's loudly against the Vietnam War, too).
Gen 3: Albert (1898-1963)/Red (1927-?). Another ouch, but it's not quite as hardcore as John and Albert. Albert's a hard-handed, domineering father. What he says goes, and as a kid, Albert more or less makes decisions for Red. Like shipping him off to the navy, or getting Red a factory job after the war instead of letting Red use the GI Bill to his advantage, so Red could go to college and become an engineer (which Red heavily preferred), or go to trade school to become a mechanic (his second preference).
Red fears his father, and fears disappointing him, or else there'll be hell to pay. Meanwhile, Albert thinks he's doing the best he can for his son, because shipping him off to the navy is better than shipping him off to the army. Which Albert proudly enlisted in as a young man, and rotted in the trenches in WWI). This results in some pretty hardcore PTSD (then called shellshock) on Albert's side of the equation, and that makes him a bit more hostile.
Such hostility and forcefulness makes Red resent his father, as Albert thinks he has to make major life decisions for him, or else he'll end up in the gutter. He doesn't like Lydia, Eloise, or Kitty. He and Bernice try to set him up with another woman, Lynn Taylor, who is seemingly "respectable" because her mother's a Morgan. But in fact, Lynn's anything but. He tries to like Lynn, and takes her on a movie date while he and Kitty are dating, which greatly upsets Kitty (quite understandably). But he breaks it off, because he loves Kitty. Not promiscuous Lynn.
At this point, Red basically flips his father off and tells him to go fuck himself. He marries Kitty, leaving a sour taste in Albert's mouth. Red married into a family of farmers*, a family of pushovers (according to Albert), and to Albert? Unlike Jerry, he's a great disappointment. Who can never be good enough, according to Albert.
*This is massively hypocritical, because Patrick came to America as a child with his destitute family of potato farmers (during the potato famine), and became a general laborer as an adult. Working in the grimy, dangerous factories in New York City. Then, John was a servant boy and chimney sweeper at an all-girls' school, moving to Point Place (with a girl he met at the all-girls' school, btw) for better opportunities the dirty city failed to provide. While converting to Protestantism for...well, calculated, non-religious reasons (he's already Irish; why maintain Catholicism when it only provides him with distinct and obvious disadvantages?).
