My Spanish ancestors developed the concept of “Purity of Blood” as a way of excluding Jewish- and Muslim-descended people from the benefits of high social class. It is rooted in Medieval antisemitism and anti-Islamism https://dornsife.usc.edu/news/stories/659/tracing-the-roots-of-discrimination/

In colonial times, “purity of blood” morphed into an obsession with lightness of skin, and the Spanish developed an elaborate hierarchy based on skin color and ancestry, called the “castas” system.

Those of us with Spanish ancestry, even as we face discrimination and prejudice, must also confront how racism is enmeshed in our own cultural history, acknowledge this, and work to dismantle it in the present.