Too many people, not enough surnames

From The Road to Little Dribbling: Adventures of an American in Britain by Bill Bryson. Page 197.

I like Norfolk. I lived there for ten years until 2013 and have grown convinced that there is nothing wrong with it that a few hills and a little genetic variability wouldn’t fix. As my son Sam used to say: 'Norfolk: too many people, not enough surnames.' I am not for a moment suggesting that the rumors are entirely true, but I will say that when the police do DNA checks after crimes they sometimes have to arrest as many as twelve thousand people.