I believe people can change. Were we all such predictable creatures of habit, there would be no surprises. People develop into themselves, which is sometimes the polar opposite of how they were raised. I don't believe you are destined to a certain lifestyle because of your upbringing. Some people fall into the mold they were expected to, but others break it.
The human race is so intriguing and fascinating. I'm only able to really gauge my own growth, but I am one of those people who keeps and rereads books. I rewatch movies. I even have a book of crosswords which are started but unfinished. I go back and fill in the blank spaces and am shocked at what I didn't know before. When I read a book again, it means more or less to me because of what I've learned since last time I read it.
When I was a kid, I kept journals (before I got so paranoid about people gathered around a campfire, reading it aloud and laughing that I buried them in the bottom of the trash can). I would read what I had wrote later on, and laugh at how silly and stupid I was. Little did I know that journal entry criticizing my previous one would again be mocked years down the road, etc. etc. -- the cycle always repeating itself.
When I interviewed potential employees for Paypal, we conducted behavioral interviews, asking for specific examples of a time in your past where this instance has occurred, and how you reacted. This is based on the belief that past behavior is the best predictor of future behavior. Many times, it is. But there were a few instances when my gut reaction was that this person is completely different now than they were then. Those are the people I remembered at the end of the day and knew would make the best employees.
I think it's the weak that believe in negative self-fulfilling prophecies. How they are defined by others develops into how they define themselves. If my parents told me I'm dumb and I'm a loser, I must be. Complacency is normal, and mediocrity seems like a prize. People who believe in something, not because they were told to, but because that's their desire, those are the people I admire. It's the strong who prove others wrong. Those are the people who we are drawn to: they become legends.
I think it's sad the way society pigeonholes certain people and makes them outcasts for life, despite the fact that they might as well be a completely different person since that mistake. If you have something on your background check, even shoplifting when you were 15 because your friend stuck those panties in your purse, you are destined to work in a warehouse or at a gas station, because all the places you really want to work won't accept that type of background.
I don't believe every person is born inherently good, but as long as we can change, there's always hope.