Quiz

It feels like I'm living among people without brains, appendixes, or wisdom teeth...

Well, I'll go home and check my version. It might be that rare case where the answer, even if not exactly what was expected, fully corresponds to the question. I can't guarantee it, but I'll check.
Anyway, if that's the case, I think the question is a trick. "The overwhelming majority of people" in this case = all normal people. A body part exists only in some, due to mutation/surgery. Perhaps it's a sixth finger, and the advertisement showed pandas.