It's not often that cultural and religious persecution makes countries more diverse, but the Spanish Inquisition might have done just that. One in five Spaniards and Portuguese has a Jewish ancestor, while a tenth of Iberians boast North African ancestors, finds new research. This melting pot probably occurred after centuries of coexistence and tolerance among Muslims, Jews and Christians ended in 1492, when Catholic monarchs converted or expelled the Islamic population, called Moriscos. Sephardic Jews, whose Iberian roots extend to the first century AD, received much the same treatment. "They were given a choice: convert, go, or die," says Mark...