I guess it is possible. I don't think there is anyone who stays the same after being born. There is always something that will change in our lives, we never remain the same. For example there are people who have changed from being introverts to becoming extroverts to some extend. You will find that when someone in their teens was quiet and shy at the same time, when they get to their teens, they start being very bold and a bit too chatty, that sometimes would get people wondering how it all happend, but it does happen and it's not surprising i guess it's just nature and it's bound to happen. Like the saying goes when you are quiet in your younger years, as you grow older you become more noisy and vice versa. Mannerisms also tend to change. I believe it has all got to do with maturity, as you mature you get to learn new things that will expose you to other things.