In response to the person who said that the mongolian spot is common in middle eastern and Mediterranean peoplex you are incorrect.... Approximately 10 percent of Caucasian people may be born with this spot as opposed to the 80 and 90 percent of those who are not Caucasian. .. I'm guessing that those 10 percent of Caucasians who are born with this spot, have some sort of nonwhite blood in them... These spots are caused by melocytes... Melanin, a substance that is greater in people of color seems to be concentrated in that area at birth.