I had a friend with a very "typically" Swedish name, whose mother moved to California after a divorce, when he was just 13. I once commented that that would explain why he spoke the American language as a native would. He corrected me to say that many Swedes, especially well-educated Swedes living in the Stockholm area, speak the American language almost faultlessly. He then said that, for example, Swedes from Upsala will speak the language properly, but with an accent which gives them away. (I don't know, maybe he had a thing about people from Upsala.)
When i knew him, i was the head bartender in a little bar in a university town, and he was one of the regulars. One evening, two jokers from Upsala showed up, and Magnus got very excited. As he spoke to them, he fell into a Swedish accent, which got thicker and thicker--at one point, he called out to the barteneder, Jimmy: "Yimmy, Yimmy, more beers!" Maybe he was just being polite to the boys from Upsala.