I got ADHD and Autism diagnosed as teen, the diagnostic was rather solid. Got methylphenidate for some months. I ran away from home with 17, i moved together with my girlfriend (at 26) into an emotionally stable environment and... the symptoms disappeared. No jactation, no special interests, no masking. Everything just disappeared. A bit of stimming remains. And a horribly fucked up sleep cycles.
Had undiagnosed RAD and CPTSD for longer than i'm self-aware. Severe emotional neglect for my first 17 years. Parental rejection plays a big part in here.
I'd be like, maybe i'm just a special case, and nothing of this applies to other people. But i see other ADHD-havers being too similar to me, and that includes hypervigilance and silent walking, which are apt adaptions to certain kind of childhood environments.
Maybe too much gets diagnosed as ADHD that is not genetic at all...