I would take anything he says about his mom with a Canadian-public-works-sized chunk of dirty road salt.
My current bathroom read is an article in The Atlantic about anxious children, and how the shrinks who specialize in this don't exactly blame the parents, but nevertheless, modifying the reactions of the parents to their anxious children is a big step in treating the kids. An extreme example is a kid who lives in a house with a playroom in the basement, and the kid is scared to be left alone down there, so the mom hangs out with him but instead of going to the bathroom, which would involve leaving the kid alone, she just pees in a bucket in the corner. The point being, in part, is that little kids need to learn to manage their fears before the fears not only become the axis around which the family revolves, but before anxious kids grow into unstable and non-functional adults.
Another example of a mother-child dynamic gone sour is the case of Ed Kemper. According to him, his mom was a vicious, horrible woman who would lock him in the basement so he didn't rape his sister. What a bitch, right? But we're also talking about a hulking brute of a man who, at the tender age of 15, murdered his own grandmother.
I will also present the example of Jazz Jennings and his parents. Jazz suffers from frequent and debilitating anxiety attacks, and Jazz and Jazz's issues appear to occupy almost all of Jeanette's available energy. His siblings appear to be normal, and they might have been better off suffering from benign neglect than they would have been had Jeanette put them in the same hugbox that Jazz has lived in. But in Jeanette's defense, she's been told by the Troon Industrial Complex that if she's less than 100% supportive, Jazz will 41% himself.
Finally, and this example may be a little further afield than the previous three, but there's a classic behavioral psych experiment known as the superstitious pigeon, where the the bird randomly gets food when it pushes a lever, like a human with a slot machine. Nothing the bird does affects whether or not it gets fed, but the bird doesn't know this, so if the bird makes a little bow and food drops, it's then always going to bow before the lever. Then when this doesn't work reliably, the bird makes a bow and a little circle, and that seems to work... for a time. These birds eventually will develop elaborate and bizarre rituals to appease the lever gods. But there are no lever gods, it's totally random. You can see some of this with parents of autistic kids, where they think, "I fed the kid a grapefruit on Tuesday and he had a good day, so we're going to eat grapefruit every day from now on."
Miriam has shaped Jon's behavior over time, but Jon has also had 30+ years to shape Miriam. Miriam is definitely the mom pissing in a bucket in the corner because it's easier than dealing with Jon's meltdowns.
Jon is a crazy-ass motherfucker, and he's up here like, "My mom's a crazy bitch who had a piss bucket in the corner of my playroom!" not realizing or remembering that he's the one who originally shaped that behavior.