I believe people have a responsibility to tell their spouse or other romantic partner, but not their parents. I had a first date last week and told the person that day. I don't like the idea of keeping secrets in relationships.
If you think you really want to tell your parents I would have some books or youtube videos (TED Talks etc) ready for them to view. It's also possible that the doctor who assesses and identifies you would be willing to meet with your family and you together, to answer any questions. My doctor offered to do that, should I be interested.
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I never give you my number, I only give you my situation.
Beatles