The Irish have Viking DNA

Irish DNA map reveals Vikings left a far deeper mark on Ireland than thought

A genetic study of more than 500 Irish men and women found Norse ancestry woven through the population, along with clues to the diseases the Irish are most prone to.

James Wilson

Sep 29, 2026

The Vikings raided Ireland for two centuries before Brian Boru broke their power at the Battle of Clontarf in 1014, and it turns out they left behind far more than ruins and artifacts. A detailed "DNA map" assembled by genealogist Gianpiero Cavalleri of the Royal College of Surgeons shows the Norse intermingled with local women on a scale historians never suspected, with the closest genetic matches found along the north and west coasts of Norway.

A “DNA map” of Ireland reveals that the Viking raiders intermingled with local women far more than was previously thought. Genealogist Gianpiero Cavalleri of the Royal College of Surgeons pieced together a detailed map after studying the DNA of over 500 Irishmen and women.

“Plenty of clues already showed that Vikings had been to Ireland, including ruins, artifacts, and Norwegian family names… The [genetic] signatures that turned up in Ireland are most similar to those from the north and west coasts of Norway, where Vikings were most active,” Cavalleri told National Geographic in 2017.

The Vikings from the Scandinavian countries began raiding Ireland around 800 A.D. and continued for two centuries before Brian Boru defeated them at the Battle of Clontarf in 1014. In those two centuries, they certainly left their mark, and in much higher numbers than previously believed.

Another interesting conclusion is that people whose families come from Ulster are more prone to multiple sclerosis than people whose roots are in Munster. The Irish overall are more likely than other Europeans to suffer from cystic fibrosis and celiac disease too.

Other trends are less unexpected: there was a clear genetic divergence amongst people whose families came from Ulster, which, ever since the Plantation era, has experienced waves of migration to and from Scotland. Other provinces showed up clearly in the results too, but Ulster was unique in this regard.