I am soooo sorry. Mea culpa. It was a wrong link
Jewish Americans show their DNA results, we not Jews WHAT?
https://www.youtube.com/watch?v=v6alUNArZAQ
A friend of mine who is of Italian ancestry and was raised Catholic converted to Judaism while she was in college. She told me that due to the history of rape of the Jewish women, the lineages are only traced through the mother since they could never be certain of who the father was. So for DNA purposes, you would have to specifically test mtDNA (mitochondrial), and not YDNA (the father's DNA). mtDNA is passed from the mother to her children — either male or female — but only the female will pass it on to her offspring, so to trace it back you go to your mother, your mother's mother, your grandmother's mother, etc. It is really difficult to trace, probably due to women changing surnames every generation. Men carry the Y chromosome and only pass that along to their male offspring, so it's traced back son - father - grandfather - down the line, and they keep the same surname down that entire line. If you suddenly find a surname that doesn't fit, it's pretty obvious what happened and when/where it happened. A third type of testing, autosomal DNA, which is what Ancestry does and which it looks like this guy did, is pretty useless beyond 6 generations. It's like a whole mix of soup that becomes very diluted quickly.
Also that guy obviously doesn't know the recent history of testing — especially companies like Ancestry — the ethnicity maps are constantly changing. My own Ancestry DNA originally showed me as 34% Scandinavian and then a few years later randomly jumped to 68% Scandinavian, so it's not accurate and they've been pretty up front about admitting that it's "constantly changing." We also have documented evidence of an Englishman + Native American marriage in Virginia in the 1600s, but my DNA shows zero North American native blood... probably because the Tribal elders here also have banned DNA testing of their population. You can only compare the DNA data of people who have submitted DNA. So if Jews have outlawed it, then the only matches showing up in his profile are those ancestors who are from outside of the Holy Land... including those early rapists.