Maturity is the ability of someone to take responsibility for his/her thoughts, actions, and feelings. The ability to make a rational decision and consider the consequences of their actions. You're right age is not the only factor that contributes to maturity, but experiences, because I've seen some elderly people behaving so immaturely and irresponsibly and also seen some young ones behaving so maturely and responsibly because circumstances have helped them to be more experienced. Success!