They occur in around 80% of Asians, and 80% to 85% of Native American infants. Approximately 90% of Polynesians and Micronesians are born with slate grey nevus, as are about 46% of children in Latin America, where they are associated with non-European descent. These spots also appear on 5–10% of babies of full Caucasian descent. African American babies have slate grey nevus at a frequencies of 90% to 96%.
What’s wild is us humans are stripped and spotted, like cows, but you can only see it in ultraviolet.
They’re called Blaschko’s lines and they’re invisible to our eyes.
Mine become visible after getting a lot of sun. It’s a little freaky but not as obvious as in this illustration.