Maybe I'm in the minority, but I feel like I've had several radical changes in personality through life. I'm not the person I was when I was a teenager. I'm wildly different from who I was in my 20s.

As I've grown and learned about myself and the world, I've become more empathetic. That's definitely had a mellowing effect to my personality.

That said, I agree that you can't suppress your identity. You might try to push it down and repress it, but some things you just can't change about yourself. But your personality is in your brain, and the brain is plastic.

But at the end of the day, all a person needs to do to have a pleasant personality is not be an asshole. If a person can't restrain themself from being an asshole, then they're probably not interested in developing their personality.