Mine have been either respectable or very good at concealing their perfidy, at least on my paternal side, which I know most about: a long line of blacksmiths, teachers, farmers and tailors, with a surprising number of doctors pre-1850. They are traceable, faintly, back to their leaving Scotland for France in the 1050s or so. They returned en masse in the 1300s some time. It wasn't religion, since they promptly divvied themselves up between a catholic clan and a protestant clan. They were often referred to as 'doctors to such and such a lord'.