I find the theories in this thread interesting, and they sound plausible enough, although that doesn't make them correct. First, the majority of posters assert their appearance of relative youth, and I do too. Why? Yes, I habitually do not expose my skin to the sun's direct rays. Yes, my face is often neutral. Yes, my clothes are simple, and my mannerisms unsophisticated. Also -- and this factor would presumably be genetics unrelated to autism -- my hair isn't rushing to fall out or turn white. So overall, I seem to get more youth than the average NT. I say this with some irony, since my chronological period of childhood was problematic, especially because I was undiagnosed...you all know what I mean. So maybe I'm just using up that "childhood resource" that NTs consume and grow out of, but I'm doing it at a slower pace. The "physical age" thing hasn't rushed, which I guess is good. But the "maturity" or "mental age" thing hasn't rushed either, which maybe isn't so good. Well, we've got to just keep plodding in the right direction, that's all.