One diagnostic criteria is "clinically significant impairment in social, occupational, or other important areas of functioning." In clinical terms, the doctor told me that someone would have to be unable to keep employment or a family in order to legally classify as having Asperger's Syndrome. (I guess so the system of disability payments would not be abused?)
But Stanford (in "Aspergers and Long-Term Relationships") points out that this criteria may be evidenced in the impaired relationships with extended family. This may be seen in the aspie rarely reaching out to them, or having little desire to be "close" with siblings, parents, or other members of the family.