The DNA of West Cork People by Mark Grace
Thanks to four DNA testers, who have West Cork O’NEILL connections, we have now confirmed (or genetically proven prefer) the outline story for the origins of some of the O’NEILLs in West Cork. The latest piece of the puzzle landed the day before St Patrick’s Day. All four have taken the male DNA test known as ‘Big Y’.
‘Big Y’ is a male line DNA test provided by FamilyTreeDNA (FTDNA) and is currently the most detailed test of its kind. For the last 500 years or so, this essentially ties all unbroken male lines to family names. All four O’NEILL testers show that their male lines are genetically connected and unbroken.
The most recent result is important for a number of reasons. Firstly, it identifies a single C16th male (MRCA: Most Recent Common Ancestor) who was the father of two sons, whose lineages became O’MAHONY and O’NEILL. This confirms the detailed genetic work done by the O’NEILL project at FTDNA and matches the various annals of Irish history that document the split into both family names known today.
Two additional testers surnamed MAHONEY and MAHANEY connect with the four O’NEILLs at this historical period, estimated to be around 1550 from DNA alone. (Please refer to my previous articles regarding the deeper historical connection.) The tested MAHONEY traces his origins to Maryland in the US at about 1760.
As previously reported, a letter written by a member of the O’NEILL family from Knocks, outlined the basic story of a young boy arriving in West Cork following the Siege of Limerick (1690) and settling in Garranes and Ballinard. While it has been a challenge to match all the detail from the letter, it has been possible using standard atDNA tests to connect O’NEILLs from Knocks with those from Derrimilleen, Reenroe & Cashelisky, and to some overseas branches.
The young lad, Sean O’NEILL, married and was reported to have had five sons. These children were likely born in the 1720-1730 period. This is now confirmed by the Y-DNA tree. All four O’NEILL testers with West Cork origins connect at a single male MRCA, estimated from just DNA alone, to about 1650. This is likely to be Sean or his father. The testers then split into two pairs.
The two testers from Derrimilleen and Knocks share the same natural genetic mutation. The two other testers, who’s surnamed became O’NEIL (with one ’l,’ due to emigration to the UK and US) share an additional natural genetic mutation downstream of this, which supports their family narrative. The latter pair share origins from a man born around 1720 who settled in Drimoleague, before his descendants moved and settled at Cashelisky adjacent to their cousins at Reenroe. This indicates that their ancestor was most likely a son of Sean. The other pair are known to descend from the man known as Felim or Filem Mor (‘Big Felix’) of Ballinard.
A genetic framework now exists for anyone wishing to investigate their West Cork male lines (O’NEILL or O’MAHONY) to check whether they tie in or not using Y-DNA, specifically the Big Y test. Normal customer atDNA tests (as provided by FTDNA, Ancestry and MyHeritage, and so on) can help tie lineages together in the post-1800 period.
I am grateful, through my previous articles, that O’NEILL descendants have shared their family stories. They remain of interest but ideally would be supported by both atDNA and Y-DNA tests at some time in the future. Hopefully, the success of this project will encourage others to DNA test.
One of the main features of ‘collecting’ O’NEILL lineages in West Cork is that most seem to have a Felix in them. My current total is around 40 people of that name. Most of these lineages cannot be connected on paper to the main framework and it is noted that three of Seans sons are yet to be accounted for, so highly suggestive many O’NEILLs in the region may actually be genetically part of the same family. Of course, there will also be those families of the name that have different origins (not from Sean) but may find themselves connecting a little further back.
As a final comment, I would like to mention the ‘rule of three’. For both of the established O’NEILL branches, and the pair of MAHONEYs, there are currently only two tests for each. Once a third tester on any of the branches comes in then the Y-DNA project will provide even more detailed mapping downstream of the already established ancestors. This opens up more rigorous genetic support for any paper trail undergoing research.
If anyone wishes advice on how best to join the project(s) and test for their genetic origins, please contact me.
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