My own surname is an extremely common one in English speaking countries, probably almost as common as Martin, yet here in New Zealand, in its population of around 4 million, the only relatives I have who share my surname are my wife, father and stepmother. I am always being told "Oh, you must be related to So-and-So", by people who assume that all who share a common family name must be related.

On an aside, and meaning no disrepect to anybody, would you call a short man who had the surname Martin a martinet?