So here's one thing that has long puzzled me — the U.S. was founded mainly by English immigrants, which is why we speak English and use many of the same names that are used in England. But some names that seem not uncommon in England are very rare in the U.S. Nigel is the one that I notice whenever I hear it (almost invariably in reference to someone from England), but Sebastian, Clive, and Simon also qualify, and I'm sure others do as well. Simon is also a pretty common name in Russia, and I'd guess in other places as well; but not in the U.S., where its frequency (1990 data) is only 0.026%, roughly at the level of Roosevelt and Forrest.
What happened? Why did those names stop at the water? Am I exaggerating their popularity in England? Were they unpopular even in England at the time the main migrations to the U.S. took place? Is there something just plain un-American about them?
Bonus question: Sergey is a common name in Russian, and I believe Sergio is in Spanish and Serge in French; all stem from a Latin gens name. Why isn't there a not uncommon English equivalent, much as Claude, Julius, Anthony, and the like are English cognates of other Latin gens names?
UPDATE: Thanks to commenter Cornellian for pointing out that Clive, which I had originally omitted, fits the same pattern.