The 1930s saw a mass exodus of Jewish scientists from Nazi Germany. Completely understandable, of course. Some of the world's brightest minds left, robbing the Germans of numerous scientific achievements.
Otto Warburg stayed.
Warburg, who won the Nobel for Medicine in 1931, wasn't exactly Jewish. His father, physicist Emil, converted to Christianity. That being said, Otto's half Jewishness should have been enough to get him kicked out of the country... or worse.
For some reason, Nazis actually reclassified Warburg as "only" quarter Jewish, and he was allowed to continue his research through the war. By the time Germany started to lose and he changed his mind, it was too late. Warburg asked to emigrate to America, but his request was rejected.
"Barely a Jew" sounds just right.