I think you need to realise that people with mental handicaps are just as diverse as people without handicaps. You find the exact same characteristics among handicapped people as you do among people without any handicap. They can be clingy, they can be stalkers, they can be creepy, you name it. Nevertheless, it's a fact that not ALL OF THEM are like that.

I've never worked with mentally handicapped people but I grew up right next to a care home (they live and/or work). Personally I knew several people who have downsyndrom and none of them is like you described.

I don't know about how the situation looks like in your area but here, children learn a lot about different disabilities at school and most parents teach their children to not treat mentally handicapped people differently than others. If they're acting "funny", it's not their fault.

Why did you decide to become a caretakers? Do you have a proper apprenticeship or something? I mean if yes, you should have learned that many of these characteristics are very typical for people with a mental handicap. Have you considered going to a therapist because of this? I wonder why you react the way you do.

Concerning the adoption thingy, I think along similar lines. If the doctors told me after the first blood tests that the embryo has some kind of a mental/physical disabilty, I would probably abort it. It's not that I don't think that they have less worth or something but I know how difficult their life in this world will be. It's not only very expensive to have children with disabilities but it's also very tough on the parents and honestly, I don't know if I were able to do it. To me it's very important that my future spouse will be on the same page as my concerning this point.