Maturity, in a psychological definition is: The ability to respond to the environment in an appropriate manner. This response is generally learned rather than instinctive, and is not determined by one's age. According to [link]
. This being said; age is just a number, not a classification of how mature you are and what you know and don't know. I am 19 and far more mature than many people I know who are waaayyy older than me. This means nothing except that in my life time I have had plenty of experiences, good and bad, that changed my life enough to learn from them. In my belief, if you really want to question one's maturity, make sure you know the level of your own. Some may not agree with this, but questioning someones maturity is not only insulting but very judgmental. especially when no background knowledge is known.
Whew. Okay, that felt good to get off my chest.