I read an article recently, I think it was in this past week’s Time magazine, that a lady sent her DNA sample (cheek swab IIRC) to different companies. Each had a different set of results. For example, one said that she was like 4% Scottish and another said 15-20% Scottish.
It seems to me that DNA testing may still have a ways to go to be as definite as many of us had been lead to believe.