Do American people share food when dining in a restaurant ?

I would say its the opposite. I don't like eating other peoples food much less actually sharing something I paid for. I know I'm not the only one. 

Some do, but I have this thing with germs from other people’s mouths and won’t eat anything someone else has already taken a bite out or take a sip from the same straw as anyone else or vice versa. I find it disgusting regardless of weather I’m related to that other person or not.

Some people do at times and others do not.

I don't, I can't stand people touching my food.