[checkyoursudo]

My aunt had celiac. She would have some real problems if she accidentally ate the wrong things. My mom tested negative for celiac several times, but she would have the same problems if she ate the same wrong things as my aunt. A more distant relative (child of a cousin or something) developed Crohn's disease (I think) and basically had similar problems as my mom and aunt if she ate similar things.

While I do think that previous posts are not wrong in that there is too much of a fad in blaming everything on gluten by people who probably aren't sensitive, we should not be dismissive of people just because some people might be mistaken. Plenty of people appear to have real problems, which, like you say, aren't always straight forward to diagnose.