of course everyone would be there, but there are average values, considered "normal", and way above the average, which is considered the autism spectrum. it's the same line, just different parts of it. i think it's diagnose only when it causes problems in everyday life, many have a whole lot of the same traits, but can still function kind of normally in society. well, what society thinks is normal at least, i'm not too sure society is right about this though.