Genetics.


Teochew genes predispose one to a few but highly exclusive traits, namely good taste, good sense, and intelligence. As you can see, pedantry is not in the catalogue, though not unheard of in poorer cousins.
That said, the reverse is not true: the possession of good taste, good sense and intelligence does not make one a Teochew. It is absolutely a matter of pedigree. Though shameful, but times being what they are, we have in recent years begun to quietly accept people who try to marry in.