I completely agree with you, most of the time it’s the parents fault for being inadequate parents in some way or another. Other times there’s also cases of children being led astray by the internet and their peers when they are young (eg. Clavicular, incel and red pill pipeline, young boys groomed into dangerous and hateful ideologies) and even when the parents try to pull them back the person refuses.

so glad this AU mentioned that children hating their parents is one of the worst case scenarios that can happen. young children are built to seek support and love from their guardians, and even when they’re abused, that love doesn’t fade quickly or easily.
this is why anytime i hear a story of a person who cut off or truly hate their parents, i’m inclined to side with the child bc i know that to make a child hate their parent, it had to have been such a shitty relationship.