Key to ancestry: The true father of Ireland

One in 12 Irishmen are descended from Niall of the Nine Hostages, a fifth century warlord, according to research by geneticists at Trinity College Dublin.

Niall of the Nine Hostages took on the English, the Scots, the French and even the Romans, at the same time establishing a series of dynasties which lasted for centuries -- and has up to three million living descendants in Ireland and elsewhere.