Three Berts went into a bar

Why do so many names have “bert” in them?  Think about it–there’s a lot, both male and female, although the female ones are usually versions of male names.  Albert, Bert, Cuthbert, Dilbert, Ethelbert, Filbert, Gilbert, Hubert…….

“Think about it?!”  Thanks a lot.  Combating my OCD, though, I’m going to answer this one quickly so it doesn’t ruin my weekend.  “bert,” from the German word for “bright,” is perhaps a part of so many American names because nearly 20% of Americans claim German descent.