Adventures with DNA
First and foremost, this is not a “how-to” guide (I’ll leave that to the experts), but rather a look at how I’ve been able to use DNA testing so far in my own research.
When the idea of using DNA testing in genealogy was first mooted, reactions ranged from those who saw it as a near-magical way of short-circuiting traditional research to those who were very sceptical about its efficacity and/or saw it as a passing fad. I fell somewhere between the two, mainly due to being married to a molecular biologist who could explain its potential and its limits to a non-scientist like myself! Later, during my post-graduate genealogical studies course at the University of Strathclyde, I learned more about the theory and practice of genetic genealogy and found it extremely interesting.
I took a DNA test with two of the main genealogical testing companies in 2017 with two broad aims: firstly to confirm certain aspects my documentary research and secondly to provide some leads concerning my brick walls – notably my unknown paternal great-grandfather. The initial results were fairly modest and (if I’m honest) mildly disappointing. On the positive side, nothing contradicted my research and there were several matches to distant cousins I already knew about. Even better, there were matches which proved that I had identified the correct partner in two unmarried couples and that (contrary to family lore) an ancestor’s husband really was the biological father of her child. However, there was nothing new which leaped out at me and there were so many matches with no surnames in common or other obvious links that I put it all on the back burner until I had more time to go into it properly.
That’s pretty much where it stayed until last year, when a couple of things happened. First Ancestry updated their ethnicity estimate based on their growing database, and my inexplicable Scandinavian percentage was replaced with an equally inexplicable large Scottish element which piqued my curiosity. Then one of my maternal cousins took a test (the only close relation to do so to date), so I was able divide my matches into maternal (the ones I have in common with my cousin) and paternal (the rest). Along with this, there were plenty of new matches to examine and time on my hands due to the pandemic.
Realising that several of these matches led back to Northern Ireland, I decided to have another look at my paternal great-grandmother from Antrim, Jane Nesbitt. The basic information I had about her came from her English marriage certificate and census returns, which told me that she was born in Carrickfergus in about 1845 and that her father was Samuel Nesbitt, a seaman. Parish records for the area are currently only available at the Public Record Office in Belfast and civil registration in Ireland did not begin until 1864 for births, deaths and Catholic marriages (1845 for non-Catholic marriages), so although civil records are available online, they were of no immediate help.
After several dead ends I finally discovered a DNA match which led back to a Hannah Nesbitt, born in Carrickfergus in about 1851, whose father was Samuel Nesbitt, a seaman: Jane had acquired a sister! I could now concentrate on the matches I had in common with this distant Nesbitt cousin and follow their lines back where possible while at the same time trawling through Nesbitt marriage records in and near Carrickfergus for potential siblings to follow forward.
To cut a long story short, by combining genetic genealogy with more traditional methods I have so far identified six definite brothers and sisters of my great-grandmother, and have DNA matches to descendants of five of them. (The sixth appears to have been childless.) Unlike their sister, all of them remained in Antrim with the possible exception of one brother, who may have migrated to Scotland where his two known daughters married. In later generations there was a limited amount of emigration to the US, Canada, Australia and New Zealand.
From civil death records I now know that Samuel’s wife was called Anne, born in about 1808, but her surname remains a mystery. In the longer run DNA matching may also be able to help here – it remains to be seen how soon I can envisage a research trip to Belfast.
Encouraged by my discoveries I turned my attention to other lines – but more of that in my next post.
 For the specialists: I realise this is an over-simplification, but my parents weren’t related to each other or to my cousin’s American mother, so there was no potential overlap between the two sides.  https://www.irishgenealogy.ie/en/