I’ll add that I’m not concerned with Jefferson. Prior to this thread, I had not heard he had been made a French citizen. However, the dual citizenship argument makes no sense, since the Constitution does not address it. The idea that a foreign country can pass a law making it illegal for a US citizen to run for President is simply bizarre - almost as bizarre as the idea that Obama considers himself a subject of Queen Elizabeth!
If “natural born” has anything to do with sole allegiance, then the Constitution does address dual citizenship.