I had to look up what a Mongolian mark was, as I was unfamiliar with the term. I'm not sure about my brothers and sister (will soon ask them!), but I do have a mark on my right calf that would probably qualify as such. My children do not appear to have inherited any Indian traits, other then my daughter tans very quickly and never gets sun burnt even though she is blond.
The Mongolian mark is at the base of the spine, extending sometimes onto the buttocks, of newborns. It does not appear on legs. They usually fade, so you have to ask someone who knew and saw you and your cousins when you were infants. It is an unmistakable signifier of native American blood.