Posted by Julie Granka on April 21, 2015 in DNA, Science

This post was co-written with Peter Carbonetto, Ph.D., Computational Biologist at AncestryDNA

For every AncestryDNA customer, we estimate the ethnic origins of their ancestors from their DNA sample—what we call a “genetic ethnicity estimate.” AncestryDNA customers can currently trace their ancestral origins to specific parts of the world, including 26 regions across Europe, Africa, Asia, and the Americas. Since the AncestryDNA science team is always on the lookout for ways to improve our genetic ethnicity estimates, we were excited about the appearance of a new scientific article in the journal Nature, “The fine-scale genetic structure of the British population.” How well do their findings match up with patterns of genetic ethnicity for individuals with British ancestry at AncestryDNA?

In the study, researchers at several universities, including University of Oxford, attempted to learn about historical trends from the DNA of people living in the United Kingdom today. They reconstructed a detailed portrait of the history and diversity of the British Isles from the DNA of over 2,000 people with deep roots in the UK – one of the most comprehensive collections of genetic data from the UK to date. The study reports several new discoveries, several of which are of particular interest to us at AncestryDNA. While their findings suggest the potential for more detailed ethnicity estimates for people of British ancestry, the study also illuminates some of the challenges in pinpointing British origins from DNA.

Teasing apart the geographic origins of British and continental European DNA is extremely challenging due to the complex history of Europe. Individuals with ancestors from Britain might find that their AncestryDNA ethnicity estimate has a lower proportion of “Great Britain” than they might expect. In fact, it is common for even individuals with all four of their grandparents born in Britain to have much less than 100% of their ancestry assigned to Great Britain.

Screenshot from the Great Britain ethnicity estimate content page on AncestryDNA. This diagram shows, from top to bottom, the maximum, 75th percentile, median, 25th percentile, and minimum amount of Great Britain ethnicity estimated for individuals who have four grandparents born in Great Britain.
Screenshot from the Great Britain ethnicity estimate content page on AncestryDNA. This diagram shows, from top to bottom, the maximum, 75th percentile, median, 25th percentile, and minimum amount of Great Britain ethnicity estimated for individuals who have four grandparents born in Great Britain.

Such estimates are due to the fact that there has historically been continuous, frequent genetic exchange between Great Britain and neighboring regions of Europe. In other words, people have moved to and from the British Isles a lot over the past thousand years or so, and their DNA has been shared with other groups in complicated ways. For example, we find that Europe West, Scandinavia, and other regions often appear in the ethnicity estimates of people with deep ancestry in Great Britain.

Screenshot from the Great Britain ethnicity estimate content page on AncestryDNA. This diagram shows, for individuals with all four grandparents born in Great Britain, the proportion who also have genetic ethnicity estimated from other regions. For example, almost 50% of these individuals have some estimated Scandinavian ancestry.
Screenshot from the Great Britain ethnicity estimate content page on AncestryDNA. This diagram shows, for individuals with all four grandparents born in Great Britain, the proportion who also have genetic ethnicity estimated from other regions. For example, almost 50% of these individuals have some estimated Scandinavian ancestry.

In our continued research into ethnicity estimates for individuals born in the UK, we also discovered that the proportion of DNA attributed to such continental European ancestry even varies by location in the UK. For example, we find the greatest concentration of Scandinavian ancestry in the East Midlands and Northern England, and we find higher proportions of Europe West ancestry in the South East of England.

Mean Scandinavia (left) and Europe West (right) ancestry proportions for all AncestryDNA customers born in different parts of Britain and Ireland.
Mean Scandinavia (left) and Europe West (right) ancestry proportions for all AncestryDNA customers born in different parts of Britain and Ireland.

These patterns of genetic ethnicity for individuals with British ancestry at AncestryDNA complement those in the recent study published in Nature. For example, one major finding of the Nature paper highlights the incredible genetic diversity of the British Isles: DNA from Western German, Northern Belgian, Danish and French parts of continental Europe all have contributed heavily to the DNA of individuals across the British Isles. This likely reflects past migration events into the UK, including Roman occupation, settlement of Saxons from the Danish peninsula, and the Norman invasion (see Figure 3 of the study). The Nature study reinforces the difficulty of estimating genetic ancestry in the British Isles because of its complex history.

However, the study also showed that by identifying “clusters” of individuals based on their DNA, the British Isles itself can be subdivided into different regions. Some parts of Britain, such as Wales, the Orkney Islands, and a third region that includes Scotland and Northern England were found to be highly genetically differentiated from other regions. On the other hand, a single genetically homogenous “cluster” covers most of central and southern England – meaning that further subdividing this region is difficult with genetic data alone (see the red dots in Figure 1 of the study).

These results suggest the potential to subdivide Great Britain ethnicity estimates into finer-scale regions, including Wales, Scotland and the Orkney Islands. Realizing this possibility for our AncestryDNA customers would require the right statistical tools and adequate DNA samples from the British Isles. First, we need to obtain adequate genetic data from individuals with deep ancestry in these regions. Second, more basic research is needed to translate these results to individualized ethnicity estimates. The Nature study only examined trends in the genetic data, and did not attempt to calculate ethnicity predictions for individual people. Despite these challenges, these new findings suggest the exciting potential for providing more detailed estimates of British ancestry from DNA.

In summary, the complex genetics of the modern-day British mirrors the complicated history of England and the British Isles. Thus, while the study underscores the challenges of estimating Great Britain ancestry from genetic information, at the same time it highlights potential ways to provide more detailed ethnicity estimates within Great Britain. As we continue to improve and refine our ethnicity estimates at AncestryDNA, we’ll continue to survey the latest science to enhance our customers’ discoveries of their ancestral origins.

 

 

 

Julie Granka

Julie has been a population geneticist at AncestryDNA since May 2013. Before that, Julie received her Ph.D. in Biology and M.S. in Statistics from Stanford University, where she studied genetic data from human populations and developed computational tools to answer questions about population history and evolution. She also spent time collecting and studying DNA using spit-collection tubes like the ones in an AncestryDNA kit. Julie likes to spend her non-computer time enjoying the outdoors – hiking, biking, running, swimming, camping, and picnicking. But if she’s inside, she’s baking, drawing, and painting.

30 Comments

  1. Cindy Barris-Speke

    You ought to test those two guys from the Cheddar Gorge area, since some years ago when they tested the DNA from bones found there that dated back 5,000 years, they found 2 men in the area that matched.

  2. Kim Sikes

    I recently received my DNA results. It estimates 75% Great Britian, 100 % Europe. I live in the USA and have relatives living here since late 1700. Can you explain?

    • Alex B

      I have very similar results, and similar ancestry. This is entirely possible considering that many of the first colonizers of the US were from Great Britain and many of them never mixed with natives, or with later immigrants. This can be explained by some original colonizers constantly migrating west as people from other parts of Europe started immigrating to the US later.

      I learned this through my family history research, because often times an ancestor of mine would move from North Carolina to Tennessee, then to Missouri and Illinois, and they were almost always farmers who married people following that same trend. This contributed to the lack of intermixing from their Great Britain DNA. As more people from different places immigrated to the US, my ancestors moved west to isolate themselves.

      So it’s actually quite common, and explainable, that people with ancestry leading to the Colonial United States period may not be very mixed with other groups that came to the US later.

      • Sara English

        What do you think people from America are? Immigrants…. unless you’re a native american it won’t show “America” as there is no “american” DNA.. Native Tribes could mean anything from Alaska, to Mexico because there were no borders at that time… The Mexican Population are Indians, Aztec, Mayan, Incan etc.. who mixed with Spaniards etc… so all of the political assimilation going on in the USA is laughable.. KEEP OUT IMMIGRANTS… good lord.. it’s not feasible considering this country was BUILD by immigrants.

  3. Lewis

    Julie, genetically, how much of a percentage of people living now in Europe, especially Ireland, Scotland and England show a genetic link with the
    Stonehenge and Newgrange locations? I am doing an educational and research project and cannot find solid information. Thank you.

  4. David

    I’m adopted & was born in the US. My Ancestry DNA came back as 100% Great Britain. Absolutely zero percent anything else. How likely is that? Could this indicate an error?

  5. Lucy

    My result for Great Britain was 8% and none for the Netherlands (Europe West). I am from Suriname that was colonized by Great Britain and later the Netherlands. What do these results mean? That I’m all British (8%) and no (0%) Dutch? Or could some of the 8% come from the Netherlands?

  6. Wanda Queen (Owens )

    I was wondering if one could gain right to reside by DNA results? Or do you have to provide exact documentation of a descendant?

  7. Cindy Alvarez

    My results showed 50% Great Britain. From what I can understand, this means the range of possible ethnicities is quite large. Is there a way to narrow them down?

    • Andrea Hamilton

      I’ve searched for the answer to the same question. My result is 60% British which I’m assuming consist of all or either, Welsh, English and or Scottish. Did you ever receive any clarification? If you don’t mind. Will you please share any information with me? Thank you.

  8. Amy

    I have an unusually high percentage of British DNA and no paper records indicating any British ancestry. How likely is it that the estimate misattributed DNA commonly found in Italy to Great Britain. My great grandparents are from the same small town in Italy with a shared surname that was in said town since the 1500th century. Here’s a link to a site about the families in that town. https://fellicarolo.wordpress.com/2012/08/13/fellicarolo-the-families/ Any plans to study the genetic diversity of Italy?

  9. Linda Jones

    I was shocked that my estimate was 69% Great Britain… With very little Irish (4%). I had always seen that Irish dna was very close to British dna. Is there a reason for the low Irish percentage? I did show 12% Scandinavian…which is congruent with your findings. I would love to hear your response.

    • David

      My sister and I had similarly surprising results. We have always thought of ourselves as having a majority Irish ancestry, and I turned up 59 percent great britain and only 23 percent Irish. My sister had a bit less Brit and a bit more Irish and Scandinavian…and knowing this, we feel like we can see that in our features, although that may be a false perception. Either way, we know that our mother’s mother’s family were all off the boat from Ireland, and given that our father’s name is Irish, we expected a greater share of Irish ethnicity in our mixes. The countries neighbor one another, are relatively small, and have had a lot of political mixing, so it’s understandable, but nevertheless surprising.

      I think we in the US have a lot more prevalent Irish visibility and pride in the Irish culture overall–as well as Italian, Jewish, and even German and to a certain generalized extent African nations–but we never, ever hear about Britain in a historic cultural sense, and so I would guess that’s really why it’s such a surprise. We just don’t think, as Americans, of the British isles as being a cultural heritage site as we do other regions of Europe and the world.

  10. Andrea Hamilton

    My result is 60% British, which I’m assuming consist of all or either, Welsh, English and or Scottish. I crave information about where my family came from. I’m American. The only DNA native here is obviously only Native Americans AKA “Indians”. I do have Native American DNA. According to my DNA results, I’m 60% British which I’m proud of. I’ve actually been reading alot about British history. Its alot to absorb. Great Britain has an abundance of history! I’m hoping that one day I’ll be able to find out if I’m Welsh, English and or Scottish. I’ll be proud either way

  11. Is there an ancestry page which gives the average percentages of each area? – that is, the average for each of the areas included in the DNA of a person from a particular area. In my case I am from Britain and most of my ancestry is from there for many generations though one grandparent and one great-great-grandparent was from Western Europe – my result gives 46% Great Britain and 36% Great Britain. small amounts of Scandinavian and Irish and traces from elsewhere. Your page about says that the average resident of Britain has 60% from there and your sliding scale suggests rouigh averages for Scandinavian and Europe West for British residents. What i would be interested to see is a page which sets these averages clearly so I can get an indication of how far my thirty percent or so of West European ancestry ghas skewed my result from the average.

  12. Ashley

    Is there a DNA test out there that singles out Scottish DNA versus English or Irish DNA? I have a 73% Great Britain and 17% Irish result, but the break down of Irish is also Wales & Scotland, which makes it very difficult to determine exactly how much Scottish DNA I carry. I have a rich Scottish history of ancestors, all the way down to Robert the Bruce. I’d love to find out how I can prove the exact percentage of Scottish DNA I carry, if even possible. Anyone know?

    • Jay

      Ashley – if you get an answer, would you mind sharing it with me? My wife and I show a large percentage of Great Britain DNA, but I really need to know what percentage of that is Scottish.

  13. David

    My family was surprised by our results. My paternal surname is of Irish ancestry, and my mother’s mother’s entire family were immigrants from Ireland, and her father’s family thought to be from Germany. My DNA came back 59 percent “Great Britain,” and before then I don’t think anyone in my family ever thought of British as an ethnicity, only a nationality, whereas we considered Irish and German/Western European to be ethnic groups. The rest of my mix was as one would expect from the region: Europe west, Ireland, and trace percentages from Scandinavia, Iberia and eastern Europe (Caucasus).

    As more information is collected, do you think the “Great British” DNA will be further picked apart? I am curious about the mix of Celtic vs. Scandinavian vs. other ethnicities…I don’t really know why, but probably primarily because as someone who has always felt to be a rather culture-less suburban American, I’m interested to know what my ancestors’ lifestyles and spiritual beliefs may have been. Does my Great British ancestry suggest druid-type paganism, for example, or is it more Norse influence or perhaps Celtic or something else? So many mysteries…

  14. Moyra Jacques

    I have discovered that I’m 97% British. Can anyone tell me what this means? Does it mean that I have no Roman or Viking dna and I am chiefly descended from the indigenous population?

    • Tegan

      Hi, Moyra. I got the exact same percentage. I am apparently 97% British, 2% Scandinavian, and <1% Irish. I knew that my paternal grandparents had both been descendants of enormously long lines of their respective families, both of whom lived in the North of England for as far back as we can see. However, I wondered at the lack of diversity on my chart, since my mum has a lot more Scandinavian in her background. Let me know what you find out. 🙂

  15. The controlled overview to emphasized the estimating a date at which an ancestral lineage originated is an interesting application of genetics, but unfortunately it is beset with difficulties and it is very difficult to provide good dates. Many people assume that the more genes the more accurate the dates, but this is not the case: some genetic markers are more suited to dating than others.Exactly the produce information well to the research, the study “resets” the debate on the peopling of Europe.

  16. Henry Freeman

    This was a great article, fantastic questions, but I’m puzzled as to why the author can’t take the a teeny bit of time to answer the darn questions!!!

Comments are closed.