I would also like to note that there are many in the past who have made great contributions to society inspite of mental or physical disabilities/injuries.

Vincent Van Gogh, John Nash, Christopher Reeves...

I have often felt concerned about passing on "bad" genes to my children. Nature and Nurture both play a role in the outcome. Perhaps we should, like Googley said, work on removing the stigmas and providing the proper treatment to allow those who would be considered "deficient" an opportunity to thrive!