Frequency histogram of a restriction site (FY-NULL) polymorphism in several populations. The frequency of the FY-NULL*1 allele is 0 in the three African populations and 1.0 in the three European populations, but lies between these extremes in all African-American and European-American populations. It is estimated that African-American populations derive 11.6 - 22.5% of their ancestry from Europeans; European-American populations derive 0.5 - 1.2% of their ancestry from Africans.