I kinda do. It seems that most people won't take me seriously or even give me a chance if they know that i'm only 14
I think many times one can tell the age range simply by the laungage (meaning, the use of words, the context in which they're used) in their postings. Also, sometimes the (much)smaller hills in their lives become the most impossible mountains, another give away. No offense, of course, it's simply the nature of the ages and stages in which we go through in life. Then again, for some people, they're forever stunted with any psycological type of growth.
I have no qualms about posting my age on here. age is a decent indicator of what to expect from a person, but as has already been mentioned, people can surprise you and be dumber/smarter than their age might suggest. and as for the discrimination thing, I don't think I've seen any of it, but I think it is equally silly to make assumptions about someone on account of their age as their skin color. some young people are incredibly mature, some old people are incredibly immature.