In many cases, the spots fade over time and are gone by the time a child becomes a teenager. Some people thought they were a "spank" or slap from gods or other religious deities. I never really gave it a 2nd thought, it was always just kind of there. I was watching a documentary on Mongolia and they talked about how a small percentage of Mongolians that are descendants Gagnus Kahn was born with blue stains on their back that usually disappear when they are a year old. Mongolian blue spots appear around the time of birth.
It led me to this site.
Mongolian Blue Spots
I recently was told what my spot is. July 14, Reply. I never had bluish marks on my bottom when I was a child just the birthmark on my shoulder. Mongolian spots often fade by themselves, but in some cases they will remain on the skin until adulthood. June 19, Reply.