I was startled to read, in Mark Buchanan’s cover article on random matrices (which have been used to explain all sorts of things) in the April 10 New Scientist, a description of the originator of the idea (in 1956), Eugene Wigner, as a “German physicist” (p. 29). Wigner was born and raised in Hungary, did university studies and then research in Germany during the ’20s, moved to Princeton in 1930 (before things got really ugly), and lived in the U.S. for the rest of his life. The Wikipedia entry refers to Wigner, accurately to my mind, as a “Hungarian American physicist and mathematician”. I’d imagine that he would have bridled at the label “German”.
[I can attest to his audible Hungarian accent in English. Early on in my undergraduate years at Princeton I had dinner, with a few others, at Wigner's house there (my girlfriend at the time was taking a course at Douglass College, in New Brunswick, from Wigner's wife). (That was just a few years before he won the Nobel Prize in Physics, in 1963; I was an undergraduate at Princeton from 1958 through 1962.)
Wigner was charming and expansive, and gave us an informal presentation on one of his lifelong interests, symmetry.]
Then there’s the case of Fritz Zwicky, described in his Wikipedia entry as a “Swiss astronomer”, though “Swiss American astrophysicist” would be more accurate. Occasionally you can find a reference to him as Bulgarian, or in a magazine article quoted by the questia site, as a “prickly Bulgarian-Swiss-American”. All this because Zwicky was born, in 1898, in Varna, Bulgaria, where his father was engaged in business for some years. But at the age of six, he was sent to live with his grandparents in Glarus, Switzerland (Canton Glarus was then and still is a veritable nest of Zwickys; the canton has supplied Zwickys to the Swiss diaspora around the world, many of them originally from the town of Mollis, where the Zwicky-Haus is located and where my Zwicky grandfather was born). Zwicky was educated in Switzerland and then moved to Cal Tech in 1925 to work with Robert Millikan. He was associated with Cal Tech for the rest of his life.
[Zwicky didn't win a Nobel, and became bitter about that, since he took an extremely dim view (which he was pungently outspoken about) of almost all his astrophysicist, astronomer, and physicist colleagues. His achievements are many, though these days he's mostly known for his proposal of "dark matter" -- an idea that was singularly unappreciated during his lifetime but is now very hot stuff.]
That brings me around to Geoff Pullum, whose own Wikipedia entry pretty much nails things with the description “British-American linguist”. Born in Scotland, he moved with his family at a very young age to England, where he was educated, all the way through the Ph.D. Then he moved to California, eventually teaching many years at UC Santa Cruz, before taking up a chair at Edinburgh (back to Scotland!) a couple of years ago. In consequence of these moves, you can find him described, one place or another, as an English, American, or Scottish linguist.
Note that “Hungarian American” (Wigner), “Swiss American” (Zwicky), and “British-American” (Pullum) all treat as head element the item referring to the national identity relevant to the major part of someone’s professional life.
In other circumstances, people can legitimately feel unsure as to whether the labels should focus on origins, current status, or preponderance in professional life, and there’s no simple solution for all purposes.