I'm rather severely Casein allergic and am anaphylactic to some molds
(penicillin family for sure) and I reacted immediately to the plain White
Wave soy yogurt. (Was only brave enough to try it twice).  So I haven't been
consuming it at all for the past couple of years, I wouldn't be surprised if
you find out that it is passed through the dairy run machinery.  (Although,
I don't know if I'm actually reacting to the cultures or something else in
the yogurt.)