I'd say experience and learning from them experiences, and common sense; but some people just appear to be more mature than others...as they say "Old head on young shoulders."
The barrel of Laughs of my families home where I was laid down for many years waiting to mature..... For what ever reason ,that never ever fully happend.....Im just a fizzy blonde that's unable to be corked.....:)D
I'm very very choosy when it comes to suitable stoppers and I'm not very fond of these new plastic new fanbled ones....there is nothing like a good old bung in the cask to get the barrel rolling about on the floor again........:)D
Freedom of thought and opinion in the home. The child's thinking not being subdued by dogmatic parents. The credit for a person's maturity should rightly go to the parents, who set the home environment.
Age and personal experiences. I wonder how one becomes jaded. My husband believes I'm not jaded. I'm older than he so, he should know? ((shrugs shoulders))
What is "maturity"? At one time when people talked about that it seemed what they meant is being able to live a responsible life in society. Now I would say it is often just something people are beat over the head with if they don't fulfill expectations. Or maybe that is "immaturity". Personal responsibility. Living and acting with the awareness that our actions and words affect others than besides ourselves. At one time it came from life, from the living of life, from experience. You run into the wall enough times you learn eventually to go around it. Or under it or over it. Now seems for many values have changed and more and more people see nobility in the banging against the wall so encourage people to just continue doing that so they never learn. Like now immaturity is often more valued to such an extent that it is treasured and cherished and encouraged and even enshrined. Irresponsibility, impracticality, romance, good intentions, innocence, and victimhood. No matter whether you can't care for yourself because it is just assumed that somehow others will or should take care of you.