And DNA research is making it even more so.
Both my father's mother and my mother did a lot of research on their families, taking them back at least until they got to the US. Neither side has any indication of anything other than Northern European ancestry - English Welsh, German, and a touch of French. When my sister and I had our DNA tested we both showed a trace of Native American ancestry - but our mother didn't.
This was fun since Mom's side has rumors (sort of like Elizabeth Warren's family) of Indian ancestry that have never been proven by research or DNA. Dad's mother's side had no hint of any in the research - but we think the trace must have come from them since Mom doesn't seem to have any. Unfortunately we never got Dad's DNA tested - he died before the prices got reasonable.
Dad's father's side was Welsh and Canadian and I have traced pretty much all of them back to when they came to America. His mother's side traces back all the way to the Mayflower or New Amsterdam. I suspect one of the numerous wives who we only know by their first name may be the source of the Indian blood, but no one has been able to find the parents for most of them.
The trace is so small that the introduction of the American Indian blood had to be eight generations back so that makes finding the specific person pretty much impossible.
I'm hoping as DNA results get more refined we can narrow it down more. When I first got my DNA tested, Ancestry only said that trace was from somewhere in the Americas. Now it is narrowed to somewhere in the Eastern US and Canada. Maybe some day they can tell us which tribe it came from and we will have a better idea!
Other than that, our family DNA just confirms what we knew from documentary evidence and family stories. We had no surprises, which was a bit disappointing. 
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