I was born with a white birth mark on my stomach about the size of an egg. I'm finnish I thought it had something to do with that because my cousins have them on their knees, my mother on her hands and my grandmother too.
When I was little I scratched my knees, and once the scabs went away I got white spots there too.
I also have moles that are surrounded by the same white and my egg sized spot had a mole in it too when I was little
I have a tiny bit of native american in me too. . . but I want to say it's a finnish thing because of the rest of my family that isn't at all native american.