I explained that while their skin was dark brown like lots of people in my family, they were not OUR cousins but were other Mexican-American people, of which there are quite many.
Shortly after that, a young-ish Chinese couple brought their 2-year-old daughter to the door. When they left, Turtle said, "Mommy, I didn't like them. Their eyes were closed."
We spent the rest of the evening in cultural awareness training.