Genetic study reveals 30% of white British DNA has German ancestry

Genetic study reveals 30% of white British DNA has German ancestry | Science | The Guardian:

The analysis shows that the Anglo-Saxons were the only conquering force, around 400-500 AD, to substantially alter the country’s genetic makeup, with most white British people now owing almost 30% of their DNA to the ancestors of modern-day Germans. People living in southern and central England today typically share about 40% of their DNA with the French, 11% with the Danes and 9% with the Belgians, the study of more than 2,000 people found. The French contribution was not linked to the Norman invasion of 1066, however, but a previously unknown wave of migration to Britain some time after then end of the last Ice Age nearly 10,000 years ago.

See also British Isles mapped out by genetic ancestry : Nature News & Comment:

Today, few Britons have ancestors from just one local region of the UK, so it is hard to identify patterns of genetic variation specific to any one place. But Donnelley and his team found 2,039 Britons of European ancestry who lived in rural areas and knew that their four grandparents were all born within 80-kilometres of each other. Since these volunteers’ DNA was a mosaic of their grandparents’, who themselves were to known be strongly linked to one British region in the late nineteenth century, Donnelley hoped to find genetic variation that clustered neatly with their grandparents' geographic location.

I was not surprised at the finding that most of the English had German ancestry, but what did surprise me was the differences between Cornwall, Devon and Somerset.

Genetic map of Britain

A genetic mapping project at the University of Oxford has shown a surprising degree of clustering in different geographical regions of the UK.

Genetic map of Britain goes on display - University of Oxford:

On the genetic map of Britain, Cornish people clustered separately from those from Devon, while the Scottish and Irish tended to share the same DNA markers. Those in South Wales formed a group, while there were separate clusters in the Welsh borders and in Anglesey in North Wales. People in Orkney were different from everyone else. In England, the majority of the South, South-East and Midlands formed one large group. Cumbria, Northumberland and the Scottish Borders seemed to share a common past. And Lancashire and Yorkshire, despite their rivalry, seemed to be as one genetically.

In the project DNA samples were taken from 4000 people whose four grandparents all came from the same area. so this does not necessarily tell about the entire UK population, but rather about those whose ancestors tended to stay put where they were born.

It would be interesting to see if a sample was taken of people whose great grandparents, or great great grandparents had all come from the same area,  as the genetic variations would probably become clearer still, though it might be more difficult to find a sample as many people do not know the names of all their great grandparents, much less where they were born. I certainly didn't know the names of all mine until I started genealogical research 40 years ago.