I was diagnosed when I was 11 but no one told me that what I was diagnosed. I, myself, knew my diagnosis in last year (when I was 19 years old)... When I turned 18, I asked for diagnosis papers from that hospital who checked me back then - heck, it taken so long to get answer.
When I first time knew it, I was little... shocked(?) but also relieved at same time. I couldn't believe myself at first but when I started to think then yeah... It started to make some sense. I dunno, I knew from teen age that there's "something is wrong on me" and "I'm not like them (others in my age), why". Knowing what I have kinda, eh, explained a lot: I found a missing piece of puzzle. I probably have hated less myself if I knew about this TBH.
My mother knew my diagnosis because she was in that investigation, but she didn't told me anything about results and my father knew nothing about diagnosis - he was always at work.
I have told my father about it now but he don't believe in that diagnosis. He's like "you was different as a child but you are completely normal". He doesn't want to talk about Asperger at all (he does help me when I need but he just doesn't believe in fact that I'm not NT).
And when I last time met my mother last summer (I see her very rarely, she lives almost other side of earth) I asked her "I found out now after 8 years that I have Asperger, why did you didn't tell anything?" and she answered: "everyone can be sick on this planet and anyone can get nowadays xxxxx syndrome diagnosis. You have nothing, I believe that you are not sick. You're just bad at making friends, you're very obsessed in your own interests, don't look at eyes..."
So...
yeah, my parents don't believes in that but I can't help them with that. u-u)