When I was about 12 my dad gave me a slingshot, not a crappy one, a really good one, I still have it. Ok maybe it is just a sling shot but you can kill people with it. Then a couple years later when I turn 17 or 18, I don't remember, he gave me his .177 pellet pistol. The point here is when your parents know you are mature they will give you what you want. My dad gave me those things because he knew that I would use them properly. Don't think that your parents don't understand a thing about airsoft they think it is best for you to get more maturity (even though you might be mature enough). Maybe you'll get a surprise one of these days.
But if you want them to really know what is airsoft, you can try to bring them to a couple of games. So that way they will see what it is. But then again it their call. But I know that you understand fully their points and the points of all those who replied to your enquiry.
Good luck and keep up the good work.
Teamwork is essential; it gives the enemy other people to shoot at. - Murphy's Law of combat
""There are no atheists in foxholes" isn't an argument against atheism, it's an argument against foxholes." - James Morrow