When considering what to write about, I remembered a 2016 press release which gives a more detailed look at British genetics which is not frequently discussed in the political right, and given the type of language used in its presentation, this is understandable. Like the mass media’s framing of the possibly dark-skinned “Cheddar Man”, a normal Mesolithic European who was not genetically a modern sub-Saharan African (LINK), the language used in the presentation of these results appears to be another ruse intended to create a narrative to justify current liberal immigration policy and cosmopolitanism in the UK. Nevertheless, the uninterpreted numerical results presented by AncestryDNA are intriguing and appear to fit with other genetic and historical information about the ethnogenesis of peoples of the British Isles.

Read the findings here, admixture percentages are included for different regions of the UK: https://www.ancestry.com/corporate/international/press-releases/DNA-of-the-nation-revealedand-were-not-as-British-as-we-think

The three largest admixtures in the British Isles are:

“British”, an Anglo Saxon admixture (Somewhat of a misnomer as the Anglo-Saxons were not the original Britons). It reaches its highest percentage in England at 35-40 %, which agrees with earlier results on Anglo Saxon admixture in England, using DNA samples from actual Anglo-Saxon graves.

“West European” French/German admixture, primarily located in the areas once inhabited by the Continental Celts (starting c. 500 BC), and likely the genetic remains of this ancient people. It peaks in Southeastern England, possibly due to the Hallstatt culture’s greater influence in that area. It also generally correlates with the geographic distribution of the mostly continental French, German and Alpine Y-haplogroup R-U152/S28 in the British Isles.

“Celtic” Irish admixture (different from the Continental Hallstatt Celts). This Irish admixture is ubiquitous in the British Isles but most represented in the “Celtic Fringe” areas: Ireland, Scotland, and Wales. This is the same pattern observed with the genetic affinity of modern Brits and Irish to Bronze Age Irish specimens from Rathlin Island (Cassidy et al., 2016), and the frequency of Y-haplogroup R-L21. It may be a genetic remnant of the first possible Celts to arrive in the British Isles in the Bronze Age. In some areas of Britain, it could also be partly imported by migrations and raids out of Ireland onto the western coast of Britain around 400 AD and about a century later in western Scotland creating the Dál Riata kingdom.

Scandinavian admixture

The Scandinavian admixture is around 9-10% throughout England and, not surprisingly, peaks in the East Midlands, the heart of what was once Danelaw territory. Trace levels (~1-4 %) of admixtures from the Mediterranean and Eastern Europe are ubiquitous throughout the British Isles.

The results obtained by Ancestry DNA show “British”/Anglo-Saxon admixture peaking, not in East Anglia (as in Martiniano et al., 2016), but in Yorkshire, the East Midlands, and Southwestern regions of England. It may be that the genetic model produced by Ancestry is able to be more accurate because it considers several admixtures from distinct geographic areas of Western Europe, helping to minimize errors caused by the aggregation of regional admixtures during analysis.

Unfortunately, I have not been able to find the knowledge of whether or not the genomes from Anglo-Saxon remains were used to define the “British”/Anglo-Saxon admixture of AncestryDNA. However, in the comments below one amateur genetics article, one individual, Bruce Petersen, with three grandparents from Denmark and one from Norway reported having 63 % “British” admixture, and 33 % Scandinavian admixture. This result suggests that the “British” admixture of AncestryDNA is indeed Anglo-Saxon, as it is found at a clear majority percentage in the approximate geographic homeland of the Anglo-Saxons (Denmark) and to a lesser degree in England, and to an even smaller degree in other parts of the British Isles which have not been permanently settled by Germanic peoples. As visible in two of the maps of England below, the regional frequencies of “British”/Anglo-Saxon admixture also appear positively correlated with those of Y-chromosomal haplogroups I1, I2, R1a, and R1b-U106, associated with Germanic ethnic groups but almost never with Celtic ethnic groups (I2 being the exception in some cases). This further supports the idea that this “British” admixture is Germanic rather than Celtic in origin. If this is true, the name of this admixture, “British”, is mistaken; it should perhaps be called a “Jutlandic” or “North-Sea” admixture instead.

The combination of “British”/Anglo-Saxon and “Scandinavian” admixture totaling around 50% throughout most of England may be why modern Danes have such a high genetic affinity to modern Brits (even compared to Norwegians and Swedes) as indicated in Athanasiadis et al., 2016. Given that about 50 % of the Y-chromosomal lineages in England are likely of Germanic origin, and given the ~50 % Germanic autosomal admixture in England, a parsimonious explanation is that nearly equal numbers of men and women migrated to England among the Anglo-Saxons, and possibly among the Danes also.

It would appear from the modern distribution of both Anglo-Saxon and Scandinavian admixture that there was likely heavy gene-flow from England into Wales sometime after the early middle-ages, possibly in the Norman era.

East Anglia and London, areas of Britain which experienced disproportionately high Romanization, not surprisingly have the greatest Italian/Greek admixture in the UK at 2.53 % and 2.51 %, and the greatest Iberian admixture at 3.43 % and 3.39 %, respectively. An obvious explanation for this is that the Romanization of these regions would have allowed for the introduction of some admixture from the Mediterranean basin, although it was only enough to have a lasting impact at trace levels.

London has the greatest “European Jewish” admixture (3.66 %) in the UK, well above that of the rest of the country, including East Anglia, at ~1.60 % or less. This may indicate a disproportionately high concentration of Jews around London at some time in history, a few of which left their tribe and intermarried with the non-Jewish population.

The Finnish-Russian trace admixture which peaks in Scotts may have been brought by Saami admixed Norsemen, or it could be a calculation error caused by the greater Mesolithic hunter-gatherers admixture in the Scotts (especially Orcadians), which is also present in Northeastern Europe.

Jayman also did an interesting post noting the percentages of some of these admixtures in the US, although one must account for the ethnic heterogeneity of the aggregate of samples for each state (you have to scroll down in his article) https://jaymans.wordpress.com/2014/05/21/more-maps-of-the-american-nations/