My wife’s friend here in El Paso is thoroughly Mexican in her heritage, but somewhere in her family’s past there’s some Irish. She’s totally white with red hair, but she is Mexican. It’s pretty wild.
That’s not unusual. Mexico is an immense genetic mixture, but somehow, dark-skinned people who seem completely Indio can have a child who looks just like one barely-remembered ancestor ... just like my husband and I got one Indian-looking child.