It's not even really that. Your home environment sets your barometer for what normal life looks like and for how strangers can be expected to behave. If your parents fight and assume ill intent in every mistake then you see that in every interaction. If they're constantly trying to get one over on each other then that's how you see human relationships. They don't have to love you or be particularly invested in you for you to learn some really screwed up lessons from them.

It is really even that. Just because it may not be logical or make sense, family bonds amd familial love are still a thing, even in families with lots of problems.