Christian Theede Christiansen, Lys mellem træer via Flickr (CC BY SA, 2.0 License)

A Genealogist Looks At Autosomal DNA Testing

By Roy L Hales

How much faith can we put in elaborate DNA based family trees that stretch back to a long vanished epoch in Africa? Have these tests shown themselves to be accurate when checked against genealogies based on written records? What does it look like when a genealogist looks at autosomal DNA testing.

Very Accurate English/Scots Results

Map showing where close to 96% of my autosomal DNA comes from – screenshot from LivingDNA website

I sent Living DNA a cheek swab last April.

The value of autosomal DNA testing was immediately apparent. This is comes from all of 22 our chromosomes and gives a much fuller picture of our ancestry during the past 250 – 300 years than sexual (paternal or maternal) DNA. While my genealogy is more precise, I can confirm that at least 90% of what the map to the left depicts in England, Scotland and Northern Ireland is correct.

This is probably understandable. I chose Living DNA because it reputedly has a large database of of British DNA.

Lack Of Southern Irish DNA

Digging up artefacts from where one of my Irish ancestors barns once stood in Flatlands, New Brunswick.

My biggest question arises from the lack of Southern Irish responses. If her family had not changed their name after arriving in Canada, my mother was a Garretty. Her great great grandfather said he was born in Roscommon. My maternal grandmother’s maiden name is Archibald (spelled Archbold in our oldest documents). Shortly after arriving in Canada, about 1830, one of our family told a French speaking priest they were from “Hilare” (Kildare) in Ireland. One of my great grandmother’s was a Ryan.

If we were talking about one family, I’d be inclined to think maybe  some of our  ancestors weren’t the parents of al their supposed progeny. When the same problem shows up in all three of my Irish stem lines, it seems more likely that the problem is Living DNA’s database.

Williams

There were a couple of surprises connected to an alleged  “black merchant” ancestor from the West Indies named “Williams”. He is supposed to have eloped with my ancestor Charlotte Taylor around 1775.  So imagine my surprise when Living DNA did not report any African DNA.

However when I emailed my cousin Mary Lynn Smith, Charlotte Taylor’s biographer, she informed me that eight of Williams’ other descendants underwent DNA testing and traces of African DNA were found in five of their tests. In addition, these traces came from widely separated areas (North Africa, Mali, Ivory Coast/Ghana and “Africa South-Central Hunter-Gatherers”).  Williams last African ancestor may have been born more than 300 years ago, which could put him/her beyond the date when we can reasonably expect DNA traces to show up. 

Williams had one more surprise for me. Living DNA reported that 1.8% of mu autosomal DNA is Welsh. Though many of my non-Irish lineages go beyond the 1700s, I had no explanation for this until the morning I remembered that Williams is one of the most popular surnames in Wales. The “coloured” middle class in countries like Jamaica arose from the physical union of slaves and their white masters. In my case, the master must have been a Welshman named Williams.

Autosomal DNA’s Long Reach

St Margaret’s Church in Hales, Norfolk – by John Fielding via Flickr (CC BY SA, 2.0 License)

The amount of DNA we obtain from specific ancestors seems to vary, much like inherited physical traits. (Who gets Aunt Betty’s peaches and cream complexion? Or grandfather Jack’s weak kidneys?)

Yet I suspect that traces of ancestral DNA can show up many hundreds of years later than expected. The only explanation I have for my 4.4% “Scandinavian” DNA goes back to the Viking era. Similarly, my 3.2% from “East Anglia” may originate with a Hales family that left Norfolk in the 1330s.

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