In other words, the same surname might have a particular derivation in Sicily, but another root in Piedmont. Unless the researcher knows the regional origin of the family, he might attribute the Piedmontese etymology to the Sicilian surname, or vice versa. Because Piedmontese is as distinct from Sicilian as Romanian is from French, onomatologies can vary considerably. While onomastic research is more likely to be accurate when the family's region of origin is known, most firms conduct such research without this knowledge. Furthermore, onomatologies attributed to certain surnames by some authors are flawed.
Onomastic conclusions are often in error where patronymic surnames are concerned.
The surname Di Cesere, for example, derives from the ancient Latin root Caesar, but this etymology has little to do with the familial use of this name in Italy today. In actuality, the Italian families who bear this surname descend from medieval ancestors who bore Cesare as a given name, having no descent from the Julian emperors of ancient Rome.