Research published in the American Journal of Human Genetics a decade ago analyzed the Y chromosome in 1,140 males from the Iberian Peninsula and Balearic Islands, and found a “high mean proportion of ancestry from North African (10.6%) and Sephardic Jewish (19.8%) sources.”

“Take the name Castro,” says Shetreet, who served as religious affairs minister under Yitzhak Rabin.

“We know it from Fidel Castro. It is a surname that was typical during the expulsion of Spain specifically for Jews of Spanish descent, and characterizes the Jews who lived in all kinds of Spanish cities that housed Jewish communities during the medieval period, such as the cities of Castro Urdiales and Castro del Río.”