Scientists in Ireland may have found the country's most fertile male, with more than three million men worldwide among his offspring.
Scientists from Trinity College Dublin have discovered that as many as one in 12 Irish men could be descended from Niall of the Nine Hostages, a fifth-century warlord who was head of the most powerful dynasty in ancient Ireland.
His genetic legacy is almost as impressive as Genghis Khan, the Mongol emperor who conquered most of Asia in the 13th century and has nearly 16 million descendants, said Dan Bradley, who supervised the research.
"It's another link between profligacy and power," Mr Bradley said. "We're the first generation on the planet where if you're successful you don't (always) have more children."
The research was carried out by PhD student Laoise Moore at the Smurfit Institute of Genetics at Trinity. Ms Moore, testing the Y chromosome, which is passed on from fathers to sons, examined DNA samples from 800 males across Ireland.
The results - which have been published in the American Journal of Human Genetics- showed the highest concentration of related males in northwest Ireland, where one in five males had the same Y chromosome.
Mr Bradley said the results reminded the team of a similar study in central Asia, where scientists found 8 per cent of men with the same Y chromosome. Subsequent studies found they shared the same chromosome as the dynasty linked to Genghis Khan.