Next time you visit Spain, take five random people off the street. No, don't literally take them off the street, just... you know what we mean. Take five Spanish people.
Odds are, there will be at least one Jew among them.
Well, it all harks back to the Inquisition (what a show!) and a forceful conversion of Spain's Jews. Many emigrated. Many converted, stayed, and integrated themselves into Spanish society. So much so that, by some estimates, 1/5 of Spain has some Jewish blood in it.
So which ones are the Jews? It's hard to tell at this point. Some last names are said to be more Jewish than other, but after centuries of integration, your guess is as good as ours.
And if you begin to extrapolate, and consider the Spain-conquered Latin America, and apply the 1/5 with some caveat (it's probably less in America because of multitude of other possible intermarriages), that still give us a large percentage of the Spanish-speaking world with Jewish blood.
A large percentage of the CATHOLIC world with Jewish blood.
Think about that the next time you visit Spain.