Not matter what is proven or disproven there will always be exceptions.
I think most people will consider a theory or actual case to their own
personal situation and if it doesn't apply to them, then it must be
flawed.  I think we all agree that smoking causes cancer.  However, not
all people who smoke get cancer or die from it.  A case in point would
be Dana Reeve who died of lung cancer at age 44 and never smoked a
cigarette.  Or what about Uncle Joe who smoked and drank until he was
94 and died of the flu?  Does that mean in either case that smoking does
not cause cancer?  I don't think so.  Just because there are 10 cases out
of 100 (or whatever the actual numbers are), that don't succumb to the
disease when all logic says they should, doesn't mean the cause isn't
proven.  Somewhere along the line, genetics or some other unknown cause
has altered the disease process and your Aunt Tilda or Smokey the ferret
didn't get the disease.  There's still alot we don't know.
[Posted in FML issue 5216]