"A leopard can't change its spots."
More and more recently I am beginning to believe the sentiment holds true.
It is an old saying but is something that is still used today.
I'm not saying that people cannot change but even if the leopard covers his spots with pain or shaves off his spots he will always still be a leopard.
Thinking about it that is quite a negative outlook from me but change isn't always good and then other times it is.