My brother got one these nationality blood test and it came back. My dad's side of the family came back from what is now germany and they all spoke german at home when my dad was growing up so they all had a pretty strong Germanic identity. The test came back showing that they didn't have a drop of german blood. Slav, french, russian, belgian, italian, british, swedish but not one drop of german blood. That was from a poor family of farmers who probably almsot never traveled from their village. So, I don't think you are going to find pure national blood lines any place except maybe in asia. Countries like China and Japan probably have had very little mixing of blood.