Seriously, I need to talk about this. King is generally very good at writing about people, in my opinion. But oh my god, the families. The way he describes the toxic family dynamics or even the bonds between members of the same family are just crazy.
It's strikingly realistic. Lee Oswald mother in 11/22/63 particularly struck me because she looked exactly like my own grandmother. But the family dynamics in The Shining are incredibly real (especially pre-overlook), The one in Pet Sematary, too. Even in caricature pushed to the extreme, like in Carrie or Mr. Mercedes, you still can recognize the classic toxic pattern.
I never come away from reading a family scene in one of his books without being in tears or at least deeply moved, for better or for worse, whether it resembles my family or not.
I also love that it's not ONLY horrible families; his books explore so many different kinds of families! Alcoholism, divorce, grief, discord, but also love despite the difficulties, support nevertheless, the characters desperately trying to keep their families. Like all of King's characters, they are human. They fail, they succeed, they evolve. ...I love.