Are ethnic groups genetically definable?
As far as scientists know, no particular genes make a person Irish or Chinese or Zulu or Navajo. These are cultural labels, not genetic ones. People in those populations are more likely to have some alleles in common, but no allele will be found in all members of one population and in no members of any other. (There may be rare variations, however, that are found only in some populations.) This cannot be very surprising, in light of the vast extent of intermarriage among human populations, now and throughout history and prehistory. There is no such thing as a genetically “pure” human population.
