Develop your genealogical spidey-sense

I still remember vividly the first research report I ever worked on. My job was to find a David Fitzgerald in East Limerick in Griffith’s Valuation. At the time, back when genealogical dinosaurs roamed the earth, the only way to do this was to identify roughly which parishes had Fitzgerald households in Griffith’s using the old Index of Surnames, and then comb through them all one by one looking for Davids. So I hunkered down and resigned myself to hours of grinding through microfiche after microfiche. But then  – what luck! – the second parish I checked, Croom, produced a David Fitzgerald.

David Fitzgeralds

As I sat down to write the report, though, doubts started to niggle. Yes, David was a relatively unusual forename at the time, but just how unusual? So I went back and continued looking. And of course, it immediately began to rain David Fitzgeralds: in Ballingarry, Emlygrennan, Ballinlough, Knockainy …

The point of this is not (just) to show how green I was. Without some idea of how to measure the likelihood of what you’ve found, its place on the scale of probability, it’s very hard to interpret it. If you don’t know that half of the population of West Cork is called O’Driscoll, and that Cornelius was extremely common  in just area, you’re likely to fall on the first Cornelius [O’]Driscoll you find and install him as your ancestor. The appropriate metaphor is the hoary old one about blind men trying to describe an elephant, each one extrapolating from the particular part they happen to touch.

Cornelius O’Driscolls

This is especially important for Irish research before the 1850s. At that point most conclusions are balance-of-probability judgements, not cast-iron certainties.

So is there any systematic way to measure genealogical probability? The short answer is no. Doubt your presumptions and go off to count David Fitzgeralds.

The long answer, as usual, is that it depends. Now that so many records are searchable in flexible ways, you can get a sense from a quick search of just how common name combinations are. So there are 107 Cornelius [O’]Driscolls in the 1901 census, but only five Cornelius Maguires. It’s rough and ready, but do it often enough on different datasets and you’ll begin to develop a genealogical Spidey-sense.

Just don’t trust it all the time.

30 thoughts on “Develop your genealogical spidey-sense”

    1. Hi Jonathan Hession. There are more Hessions…I have some too..Not sure from whence they came but there they are..I think with my Campbells who are from Ireland…

    1. I think I win the prize… John Gallagher? Hugh Gallagher?
      My satisfaction with this search appears to be what I learn about Ireland and genealogy in general because the Gallagher thing is slow going.

  1. I bet none of you want my elusive ancestors – James Smith and his wife, Mary Brady (daughter of Patrick), from Cavan!!

  2. Trying to pin down Michael Flatley in County Mayo around 1820 still gets feedback about Tippy Toes in this century!

  3. On my Irish side I have McDermott. Not too many of those. But worse, on my Swedish side I have Peter O. Peterson. Oh Peter! This is a curse.

  4. I feel so much better now. I have Jim Jones my grand-pop, Michael Smith my great-grandfather and Adolph May or Mai, my other great grandfather. Over 500 James Jones came up on one site for the year of his birth. For Adolph May, every record in the genealogy kingdom that took place in the month of May for all years came up! Then I have 4 different Murphy families, Kelly’s, Sullivan’s, Brennan’s and Carey’s. It sure is a challenge and I love a challenge.

  5. I have used spidey sense ways to give a kick start to the direction to go in. My father often said “och yes”but was supposed to have Irish origins… yes,but turns out there are Scottish ones too. Slang and sayings can be interesting. If something was untidy Gran would say “its like a pac ar poo ticket”. It actually is a Chinese gambling game using tickets with the odds scribbled all over them.I found that in her youth she lived not far from China town! It is like ghost clues! (and I have an overactive imagination)

  6. Or what about when your research leaves you completely stumped about what the name actually was. Duignan or Degidan? Or neither? This in an area (Cois Fharraige) where either surname is (still) pretty uncommon, and all the individuals you have examined were likely to have been monoglot Irish speakers …

    1. My Michael Ryan, from Tipperary, had a son Patrick Ryan, which didn’t exactly narrow things down!

      (I did eventually find them, though, thanks to some important clues in the Canadian records, but it took me years…).

    1. You sure that that first name isn’t ‘Finton’ just transcribed badly? Never heard that name anywhere before.

    1. Adelaide,
      Thomas Ward is researching the Ward family in county Galway. You may want to check out his Ancestry page it may be helpful.

  7. Well I will add mine John Walsh from Mayo, who’s son was John Walsh, who’s son was John Walsh, and his son John Walsh my grandfather

  8. Well how is this…I have John and James HIGGINS and can’t find any anywhere..Tipperary..No one answers my plaintive cries for help….

  9. Well, you know, the name is carved in a grave slab in Killallaghtan cemetery. It could be Tillon or Titton, but I am afraid probably not Finton. But, I am open to any possibility……

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