If you have Irish Catholic ancestors like me, you have probably hit a wall once you reach Ireland.
When Conan O’Brien had “Who do you think you are” producer Lisa Kudrow as a guest on his show in 2015, Kudrow said “Irish Ancestry is tough, because… you all have the same name!”
She wasn’t joking. Take one of the most common surnames in Ireland, Byrne. It wasn’t just the fifth most common surname in 1891, but the entire clan is centered on the east coast around Dublin.
I’m Mike O’Neill and I’m a big data professional and amateur genealogist who has made tons of mistakes since I picked up genealogy as a hobby in 2011. I want to help you avoid some of my screw-ups.
Before we get to surnames, if you didn’t already know, the biggest challenge in Irish Catholic genealogy is the lack of a census before 1901. It’s not that the English didn’t take a census of their subject, Roman Catholic population. They did.
But during the Irish Civil War, in late June and early July of 1922, pro- and anti-treaty forces clashed around a Dublin government building complex, the Four Courts. As part of the fighting, the Irish Public Records office—including the 1841, 1851, 1861, 1871, 1881 and 1891 censuses along with nearly a thousand years of other Irish records—went up in flames.
Back to surnames. In 1894, the Registrar-General of Ireland, Sir Robert E. Matheson, tabulated surnames from the 1891 census, and published a Special Report on Surnames in Ireland. The top 50 surnames in Ireland amounted to 22.4% of the population. In comparison, in England, the top 50 surnames amounted to 17.8% of the population. Scotland was worse, though, with the top 50 accounting for over 28% of the population.
Surnames in Ireland also tend to be condensed in particular areas. Matheson also looked at surnames from birth records in 1890 to show where. For example, 78% of Murphys, the most common name in Ireland in 1891, were in southern Ireland.
Pick any surname in Ireland, and you’ll probably see similar patterns. The Gallagher surname, concentrated in County Donegal, is fairly common around northwestern Ireland. O’Neill is more distributed, with three concentrations—one in Ulster in the North, a second around Dublin, and a third County Cork. And Kelly appears just about everywhere.
Catholic forenames were also heavily reused. In a study examining how Irish immigrants stopped using traditional names for their foreign-born children, 11% of first generation Irish males in England in 1881 were named Patrick, while ~9% of females were named Bridget.
So… if you’ve got a Patrick Murphy or a Bridge Gallagher in your family tree, it’s a safe bet there will be at least one other person with the same name and of the same age in the county you’re searching.