Sorry I dont believe the same. Why? Because I've been the same person my who life. I've never changed, but in my life I've changed schools 4 times, and have moved. My surrounding, and friends might have changed, but I never did.
Then take my friends as a young child. I'd lost real contact with them up until recently with facebook, just yesterday over dinner me and my mom were talking about how none of them changed. They all grew up into people we always thought they would.
I feel that peoples personalities are rather set from a very young age. You might change in style, taste, beliefs, or mold yourself into a frame that fits in with certain groups, but in the end your always that same person inside. I feel it take alot, an extreme amount of will, or trauma to change that true inner person.