Differences Between Scottish & Irish DNA...

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Differences Between Scottish & Irish DNA...

Chapters:
0:00 Intro
0:23 Differences Between Scottish & Irish DNA
3:13 Gaelic Corridor and Gallowglass
5:02 Get Member-Only Videos
5:15 Red Hair & Disease Rates
6:04 Scottish & Irish DNA Haplogroups

Are there DNA differences between Scottish and Irish people, and if so, how different are they? Many people may think that the two are pretty much identical, but is this true? Now the ancient DNA of both Scotland and Ireland is very similar in general. They are a mixture of western hunter gatherers, EEF and steppe ancestry, which was introduced by the Bell Beaker Culture. Yet one key difference between Scotland and Ireland is the level of Anglo-Saxon ancestry. Scotland has more Anglo-Saxon DNA than Ireland on average. And this is largely concentrated in the south and southeast, with estimated levels of 15-30% in parts of the Lowlands.

Now this is largely due to the historical expansion of the Kingdom of Northumbria, which stretched up the southeast of modern Scotland, up to Lothian and Edinburgh. I should note that there is a East-West divide in Scottish DNA in general. The Scottish Lowlands, especially to the east, generally has a genetic profile closer to that of Northern England. Whereas in the Scottish Highlands, Argyll & the Western Isles, there is more of a Insular Celtic genetic profile that closely matches Ireland and Wales.
Now Ireland overall has a lower Anglo-Saxon influence (typically below 10%), as this breakdown shows. Ulster in the north generally has a little more of this ancestry than other regions, partly due to the Ulster Plantation, as well as other events down through history.

But what about the Normans? Well Scotland and Ireland both experienced some influence from the Normans, but the overall impact in both was generally modest, and largely confined to elite families. So the Norman influence is similar in both Scotland and Ireland, but Anglo-Saxon ancestry is higher in Scotland. Now another differences between Scottish and Irish DNA comes from the uneven impact of Viking settlement across the region.

Sources:

E. Gilbert et al. The genetic landscape of Scotland and the Isles, Proc. Natl. Acad. Sci. U.S.A. 116 (38) 19064-19070, https://doi.org/10.1073/pnas.1904761116 (2019)

Gilbert, E., O’Reilly, S., Merrigan, M. et al. The Irish DNA Atlas: Revealing Fine-Scale Population Structure and History within Ireland. Sci Rep 7, 17199 (2017). https://doi.org/10.1038/s41598-017-17...

Shanmugam, A., Merrigan, M., O’Reilly, S. et al. A genetic perspective on the recent demographic history of Ireland and Britain. Eur J Hum Genet 33, 538–545 (2025). https://doi.org/10.1038/s41431-025-01...

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