The same is true of the opposite, though. Like, if a kid is severely mistreated, it can affect his or her mental health.

However, giving a kid too much freedom (and therefore, being too nice) can, hypothetically, affect his or her mental health (for the worse).

I tend to think me and my siblings suffer from the latter.

Either way, I do think that everything is part genetics, part environment. I'm not sure anyone can change my mind on that.