Is it necessary to be mature adults to be gentlemen? With the reference to "Two Gentlemen of Verona" illustrate your position.

The two young boys did many things to make a living. But they never spent anything on themselves. They lived shabbily. Even the narrator was astonished to see the boys working so hard. However, the boys never complained. They ran all kinds of errands to save money for their ailing sister who was undergoing treatment. They never disclosed their hardships before their sister or anybody else. The two boys earned handsomely, but never bothered about their own needs. They could have splurged it all if they wanted - to but they never did. The care of Lucia and her treatment were their utmost concerns. They loved their sister very much and shouldered her responsibility willingly. 
Thus it is not necessary to be mature adults to be gentleman.