Genetic Clustering in the U.K.

A recent gene study of native Britons shows, among other things, that Celtic Britons do not have a common ancestry.

Britons in the "Celtic fringe" of the West Country, Wales, Scotland, and Northern Ireland can be divided into half a dozen or more distinct genetic clusters. They don't show a common genetic profile compared to other Britons from England. The current genetic clustering of native Britons thus predates the arrival of the Celts. The clustering also shows that Angles and Saxons intermarried with the native Britons they encountered, rather than replacing them when they arrived in the island in and around the 5th century CE.

This is a fairly common pattern throughout history; compare the Aryan migration into southern Asia, and the Spanish conquest of Central and South America. In both cases, there was a transfer of language and culture (by the Indo-Aryans and Spanish, respectively), without a wholesale replacement of the native population.

This type of study could potentially answer many historical questions about population movements; I hope similar studies are performed all around the world.