OK. What I mean is all we did was read books to her as I presume most parents do - we didn't try and teach her to read in any formal way - but when we met up at toddler-group things, whereas most children were essentially unable to read much at all other than their name, she was picking up books and reading them out loud so it was pretty obvious she could read.
I think their is a distinction between learning something and being taught it. I learned to use Excel, for example, because when I started working it was on my computer and I realised it could be useful, (it was a long time ago!) so I experimented it with it until I could use it. Later on, when loads of people from the department were bringing me their spreadsheets to fix, I was asked to run training days to teach them. The outcome is the same, and I'm not suggesting one is superior or inferior to the other, but the process is different, I think.
Anyway, the thread title is 'How did your child acquire the label?' and my answer was (not very well expressed) but that once she started reading books to the other kids when she was at toddler groups, the other parents with whom I was friends began to say things like 'you DD is really clever isn't she?' - I guess it doesn't massively matter if she taught herself or not to be honest, just the fact that she could read fluently at that age, regardless of how she acquired the skill.
Just for clarity, as I can't properly assess the tone of your reply (because I am also ASD, and because I'm used to people being dismissive), she has since been assessed by an Ed Psych as being on the 99.5th percentile for age. The reading was the first clue.