How can I get my parents to ignore the fact that I do not fit social norms?

Well, I don't think you can get them to ignore the fact that you don't fit social norms. Not fitting into social norms kinda makes you stand out by itself. You make a lot of good points, but I feel like you lose a touch of humanism if your arguments. The goal of leaving the world a better place is one worth striving for, but some many of the little things like human contact leave the world a better place all the time. Smiling at a stranger makes their day better. I wouldn't worry so much about passing on the genetic disease either, science has come up with plenty of prophylactic methods to safeguard against that possibility if you chose to go that route :) I'd recommend you explore humanity a little more, you might find something worthwhile in people, and that in turn will help you make the world a better place in the long run as well.