Some families should never have existed in the first place. Minor incidents get hijacked by the resident sociopath and used to control people. I've seen that in my life and friends'. It's usually the father IME. Nobody else wants to rock the boat, you get splits along a timeframe of years. What's especially galling, and I've seen this across the board, is a mother sticking by said scumbag when her children are victims as much as she is.

That's not to say it's always fathers either. My grandmother used to bring up her sons' dead father just to watch the reaction... People get worse as they age in this regard.

my grandmother was abusive and generally nasty. Both my aunts have very severe mental health issues as a result. My mother only started to talk about the hardship she experience in her childhood recently. Because of all this back story, I don't have a good relationship with her either and only talk to her when I have to.

Families are not always best and sometimes it's just preferable to break the circle.

Parents are different. You are not just 'related' to them. Whether they are good parents or bad they still brought you up so extra effort should be made to maintain a relationship.

Especially as parents get older and may need your support.