What's interesting is that it seems that tradition began in Roman times (think of "Cicero" which actually means "chickpea" and which might have related to him having a wart).

Also I read recently that there is a regional difference, in that the scribes in southern Italy wrote the surnames in singular (ending in -o) while the scribes in the North wrote them in plural (ending in -i). Of course, with the migration from the South to the North following WWII there are now North-Italians with surnames ending in -o.

I'm just a Scandinavian with a bog-standard patronymic surname too, haha.