Does maturity comes with age?

Why do we generally expect “teenagers” to act like teenagers and a little "older" people to behave soberly? Why do we assign the moods to age groups? Why do we look with surprise if a person of 60 is cheerful and fun loving, whilst a teenager is talking about the philosophy?? How do we measure maturity? Is it measurable?? What are the reasons of maturity? Is this life experience that comes with age or does one get it from listening to parents, grandparents, reading books?? Does being mature mean that one is less fun loving or can someone be mature and be fun too??Does one have to sacrifice one for the other? I think maturity comes with experiences and the way we think. If we are too much into outside world and less within we tend to mature late. There has to be balance of communication between the world outside and the mind within for a person to be mature. Whenever a person achieves that balance between thinking and interaction with world and within himself, he becomes mature. But the maturity is not always there...we can act immature in between whenever we lose that balance.