GENETICISTS have identified Ireland’s most successful alpha male. As many as one in 12 Irish men could be descended from Niall of the Nine Hostages, a 5th-century warlord, according to research conducted at Trinity College Dublin.

Niall, who was head of the most powerful dynasty in medieval Ireland, may have left a genetic legacy almost as impressive as Genghis Khan, the Mongol emperor who has 16m descendants after conquering most of Asia in the 13th century.

Researchers at the Smurfit Institute of Genetics at Trinity estimate there could be as many as 3m men worldwide descended from Niall. The highest concentration of his progeny is in northwest Ireland, where one in five males have inherited his Y chromosome.

The High King at Tara from 379 to 405, Niall founded the dynasty Ui Neill, which means descendants of Niall, who ruled Ireland until the 11th century. He reputedly made raids on the coasts of Britain and France, including one that netted St Patrick, then a slave called Succat, who was brought to Ireland.

Niall is said to have subdued his enemies by taking them hostage and he established small kingdoms in Wales and France, where he was eventually killed. His children were also powerful kings, particularly in the northwest.

The Trinity study examined the Y chromosome, which is passed unchanged from father to son, in males around Ireland. Laoise Moore, a PhD student working on the Wellcome Trust-funded project, took DNA samples by mouth swab from male volunteers and recorded the birthplace of their paternal grandfather.

Dan Bradley, who supervised the PhD, analysed the genetic fingerprints of the samples and found the same Y chromosome in 8% of the general population, with a cluster in the northwest where 21% carried it. This unexpected anomaly reminded the geneticists of the similarly common Y chromosome found in central Asia and believed to be Khan’s.

They calculated that the most recent common ancestor was likely to have lived about 1,700 years ago. Coupled with the geographical distribution centred on the northwest, this pointed to the Ui Neill dynasty.

The researchers then checked genealogical records, which recorded the relationships between different Irish families over centuries. Katharine Simms, head of Trinity’s history department, provided the geneticists with a list of modern surnames linked by genealogical tradition to the Ui Neill dynasty.

“We found that the frequency of this variant, this Y chromosome, was much higher in this group,” said Bradley. “That was the clincher — the Ui Neill, this group that held sway and power in Ireland, seemed at some stage to have had a single patrilineal ancestor.

“It’s another example of a linkage between prolificacy and power. It confirms these medieval genealogies.”

Among those who carry the distinctive pattern of Y chromosomes in their genes, indicating probable descent from the warlord, is Bradley himself. “I’m from the northwest, so it is not that unusual,” he said. “One in five of the people I would meet on the street at home would also be descended.”

When international databases were checked, the lineage also turned up in roughly one in 10 men in western and central Scotland. About 2% of European-American New Yorkers carried similar Y chromosomes.

“Given historically high rates of Irish emigration to north America and other parts of the world, it seems likely that the number of descendants worldwide runs to perhaps 2-3m males,” according to the paper, which has been published in the American Journal of Human Genetics, which is also where the study showing Khan’s genetic dominance appeared.

Niall reportedly had 12 sons, many of whom became powerful kings themselves. One was Conall, after whom Donegal (Tir Chonaill) was named, while Tyrone (Tir Eoghain) was ruled by Eoghain. Other sons were powerful in the midlands and all but two of the High Kings at Tara after Niall were his descendants.

Because he lived prior to written records, there had been doubts Niall was a real person.

“This genetics is very exciting because for the first time you are taking about real people,” said Fergus Gillespie, the chief herald. “The light these surveys are throwing on who the Irish are is fascinating. It verifies the genealogy and answers a lot of questions.”

Powerful men in medieval Ireland had many wives and children. Divorce and concubinage were allowed and illegitimate sons were claimed and had rights under law.

“Under Brehon law a man had a first wife, a live-in concubine, a live-out concubine and someone he just casually met and so on,” said Simms. “In each of these cases a child could take the father’s name.”

Modern surnames tracing their ancestry to Niall include Gallagher, Boyle, O’Donnell, O’Doherty and O’Kane. Even in the 15th century, Niall’s descendants were producing offspring in abundance. Lord Turlough O’Donnell, who died in 1423, had 18 sons with 10 different women and had 59 grandsons in the male line.

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