Story sounds fake although I know things like this happen. After my lady shared her stories about her autistic students struggling to control their sexual urgues, I learned to understand that people with special needs have the same urges as so called "normal" people...
What I don't understand about this story is why the the family refuses to acknowledge that the down syndrome family member don't have sexual urges? They should try to hook the family member with someone who also has down syndrome..
Dude need to just stay away from family functions if he got mental and emotional issues himself..