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It's the blockbusting US fantasy drama that has become infamous for its lashings of violence, sex and gore.

But what homegrown critics of bloodthirsty medieval saga Game Of Thrones might not realise is that, here in Wales, its tales of warring noble dynasties might not have been that far from the truth.

Indeed, according to groundbreaking research into the ancestral DNA of the nation, it seems a staggering quarter of all men in Wales with four Welsh grandparents can actually claim to be descended from about 20 rulers from the Dark Ages period – kings, warlords, or other powerful men who governed the land around 1,500 years ago.

“There’s a definite game of ancient thrones going on in Wales, that’s for sure,” said Alistair Moffat, the man behind CymruDNAWales and its unprecedented attempt to trace the origins of the country’s people back to around 9,000BC.

“By looking at clusters of very similar Y chromosome or fatherline markers geneticists can detect the signs of what is known as social selection.

“This is a coy term for the undoubted fact that powerful men in the past often had a great deal of sex with many different women, thereby spreading their Y chromosome very widely.

“It’s as simple as that and a lot of it went on in Wales – which means there are hundreds of thousands of men walking the streets of Cardiff, Caernarfon, Swansea and Newport who are the direct descendants of these prehistorical patriarchs.

“Or, to put it into sharper perspective, it means that 25% of the male section of the home crowd in the Millennium Stadium during international day are descended from royal or noble families.

“What is more they’re also cheering on a team with about four players who are also descended from the high born.”

By using some of the most advanced genetic testing to date, Alistair added that scientists are now able to track the roots of those first immigrants who came to settle in these lands around the time of the last ice age.

And key to unlocking this mystery are the six billion letters of DNA we inherit from our parents (three billion from our mother, the remaining other three from our father) in which mutations – known as markers – can occur.

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These can, via a simple saliva sample, be located and dated and their journey here, often from far-flung parts of world, can be mapped out – ancient lineages that can often result in some very surprising discoveries.

For example when the same programme was carried out in Scotland in 2012 it threw up the surprising revelation that more than 1% of all inhabitants there were directly descended from Saharan tribesmen – while the actor Tom Conti discovered he shared DNA with none other than Napoleon Bonaparte.

“But who were these fertile and enthusiastic warlords and kings who lived following the fall of the Roman province of Britannia, at the time early Welsh kingdoms such as Deheubarth were emerging?” said Alistair, whose previous similar venture in Scotland succeeded identifying Royal Stewart DNA.

“Well, we just might find out by testing as many men in the modern population as we can to see if their DNA matches and forms clusters to suggest descent from a single person.”

And having Carmarthen-born Game Of Thrones star Iwan Rheon as the latest celebrity to sign up to the ambitious project – alongside the likes of Michael Sheen, Rhod Gilbert and Max Boyce – is a definite step in the right direction, he added.

“The interim results of the CymruDNAWales project are already very striking.“We all suspected that Wales was a Celtic country but no-one was prepared for just how much – the classic Celtic Y chromosome marker R1b S145 being carried by a whopping 45% of Welsh men, as opposed to just 15% over on the other side of Offa’s Dyke.

“We have always known that Wales is different from England, but now here is a statistic that shows there is no question about it.”

For more details about the project visit www.CymruDNAWales.com