Hehe, I see that all the time. I thought I was old being diagnosed at 20!

The thing is, we didn't really know a lot about autism when you guys were kids (and, for that matter, precious little when I was a kid; I'm 27 now.) Lots of diagnoses got missed; they had very narrow criteria for a long while. Nowadays, they've expanded the criteria because they realized they had been arbitrarily narrow; they're including people who learned to speak on time (the Asperger's type) and they're re-evaluating people who also have some other diagnosis. I read one study about institutions for mentally retarded individuals, in Texas I think, who were re-evaluated--and quite a few were found to have autism instead of, or in addition to, the MR they were already known to have; all of them missed diagnosis. So that's really common for all kinds of autism; only the really, really obvious, stereotypical cases got diagnosed when people in their forties today were kids. If you were off the stereotype for even the most trivial of reasons (I, for example, am a girl)... you didn't get a diagnosis, and nowadays doctors are scrambling to catch up, to try to figure out what's autism and what isn't after the person's spent a lifetime trying to learn coping strategies.