I have a "need-to-know" policy regarding financial info, personal ID info, and medical info, including about my Asperger's. If they don't need to know I don't tell them. I do reserve the right to make occasional exceptions, like in telling family members if I wish. So far only my sister knows, but she figured it out on her own, and I confirmed it when she told me she believes I have Asperger's. I recommend you use the same system. Only tell people who need to know, with occasional exceptions for people close to you. In the case of dating, I would wait through several dates first. If things look like they are getting serious, then you can tell them serious stuff about yourself. There is no need to tell serious stuff to someone before that point. You have a right to keep private stuff private. At the same time, someone you are developing a serious relationship with has a right to know what they are getting into.
In the case of STDs you should discuss them before becoming intimate the first time. STDs are contagious, and some can cause lifelong problems. Some can cause cancer, and some can kill you or your partner, so these need to be discussed prior to being intimate.
Fortunately, Autism spectrum disorders are not STDs. However, they are often genetic in source, so it can be passed on to children through the genes. Because of that, this needs to be discussed with a potential mate ahead of marriage.
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If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau