I was diagnosed just recently at age 36. I met a couple who had an autistic son who stimmed regularly in public. He made some of the same odd movements that I had made my whole life, only I usually did them in private. I thought I was just a strange person and never considered it was neurological in nature. Meeting him led me to think that autism may have been the source of my stimming. As it turned out, it was! The diagnosis not only explained my stimming, but so much more.