That is my piece of advice that you can use, tell the truth. Tell the parents that you aren't good at talking to people and you are sometimes not interested in what people have to say, and it may be your own fault, and you apologize for offending them, but it is something that is a part of you. Just say what's up. You don't like social BS, then tell the truth and keep it real and if that doesn't work, whatever. Keep in mind when I say "tell the truth" I don't mean be a douche and snub the parents and claim your superiority, I mean tell them that you aren't good at socializing.
Mmm... I don't know about this part. A lot of people instinctively connect the dots in such a way as to say that any type of disorder which hinders your ability to act normal is seen as being a retard. You wouldn't want that at all.