within Mexican populations, people tended to pick partners with similar proportions of Native American and European ancestry, while in Puerto Rican populations couples had paired up based on their shared balance of European and African ancestry. [. . .] presumably people had cued into subtle variations in appearance, behaviour and even odour.The paper ("Ancestry-related assortative mating in latino populations") is open access.
"I think it's fascinating," says Burchard. "People are sizing up their partners, maybe in subconscious ways."
Assortative mating by genetic ancestry in admixed populations
Via HBD Books, "Guapa, it's your genetic ancestry I love":