Genetic Ancestry Testing and Race

Ever since the Brexit referendum racial attacks in the UK have been on the rise but unity and respect have risen up from the masses as people come together. More than ever it has become important to break down the barriers that cause division. Last year Momondo’s video to do just this went viral. It featured a range of people from all over the world taking a DNA test to determine their ancestry after giving their (usually racist or nationalistic) comments. The sentiment behind the video was simple as one woman says: “There would be no such thing as extremism in the world if people knew their heritage like that. Like who would be stupid enough to think of such thing as…a pure race?” She is absolutely right even though the video was criticised: For one thing, actors had been used and the science was off.

Determining ancestry is not as clear cut as some companies make it out to be and in fact it has been described as “genetic astrology”. In other words it doesn’t really tell you anything useful and here I will explain why.

 

Genetic Testing  101

Genetic testing is carried out on three types of DNA: Mitochondrial and Y chromosomal DNA (which are passed down the female and male lines respectively), and the autosomal DNA (where you inherit 50% from each of your parents). Analysing the Y chromosome or the mitochondrial DNA is pretty straightforward because they are inherited as one unit. The results from these markers usually come in the form of a haplogroup (basically a type of group), the geographical and chronological origin of the haplogroup, and the frequency of this haplogroup in varying countries around the world. By comparing haplogroups, migrations and population history can be inferred BUT it will only be explaining one part of your background; just the mitochondrial and Y- chromosome inheritance.

 

These are not the ancestors you are looking for

Analysing autosomal DNA to determine ancestry is more of an issue because it is such a patchwork of genetic sequences. The first problem is that it undergoes recombination where varying fragments from both of your parents are joined together. It also occurs quite randomly so this means there will be sections or genes you won’t inherit from your parents. If you go back far enough you will find that you won’t always inherit genes from all of your ancestors. Therefore in your family tree you will have ‘DNA ancestors’ the ones who passed on their genetic material to you, and ‘pedigree ancestors’ the ones who didn’t. Genetic ancestry testing will only ever be able to detect your DNA ancestors, which is not entirely accurate.

 

The different stories of you

The second issue comes in on what gene/ section of DNA you are analysing. Each different gene or section of DNA will have its own ancestry. This is akin to analysing a man’s Y chromosome and his mitochondrial DNA. He will get two completely different stories; his paternal grandfather’s lineage and his maternal grandmother’s lineage. If you apply this principle to autosomal DNA, you can get different sections of DNA telling you different ancestries. Not all genetic companies will look at the same sections of DNA thus you end up getting different results entirely.

 

Your DNA match or origins?

Finally, the third issue comes in the results itself and is where I want to put the emphasis. Results come in the form of percentages; how much of your DNA is said to match to a current population- and this is the most important point. These percentages do not indicate where your ancestry lies because your DNA is being compared to DNA of a modern population that exists within a defined current country with geopolitical borders. At its core, this result indicates a frequency match not origins! Ethnicity is a social category not a genetic one and this is where the Momondo video was inaccurate because there is no such thing as a British/ French/ African/ Celtic/ Viking gene!

 

There have been so many migrations by humans since we first left Africa about 100,000 years ago and borders of countries have changed throughout history by rulers due to geography and the politics that genetics can’t be linked to nationality. This video shows just how much borders have changed in the past one thousand years within Europe.

 

Britain is the perfect example to illustrate this. Homo heidelbergensis and Neanderthals were the earliest inhabitants of Britain. Modern humans arrived into Europe and Britain approximately 43,000 years ago. Right before the Ice Age, there was a population replacement throughout Europe indicated by ancient DNA. Then the farmers that left the Fertile Crescent 11,000 years ago took two routes through Europe arriving in Britain at about 6-7,000 years ago. The Beaker people during the Bronze Age arrived about 4400 years ago. Then we see the Roman invasion in 43 AD followed by the Germanic Anglo-Saxons from 400’s AD, the Scandinavian Vikings from the early 800’s AD and the Normans from France in the 11th century. With each migration (and these are just a few!) people would have settled and mingled with the current inhabitants which have occurred throughout historical times and up to the present day. With more mixing and different rulers, borders will have changed and people with similar genetic backgrounds would end up having a different ethnicity entirely. A paper by Leslie et al 2015 tracked all the prehistoric migrations and how each of them contributed their genetic material to the population at the time. Interestingly not all migrants contributed equally and evenly across Britain.

 

Image from Leslie et al 2015 “Major events in the peopling of the British Isles”
Image from Leslie et al 2015 “Major events in the peopling of the British Isles”

 

 

 

 

 

 

 

 

 

 

 

 

 

What does this mean for people who get genetic ancestry testing? Not much. The results are inaccurate. They are not giving you your origins and therefore have been described as a waste of time and money.

What does it mean for British people and their ancestry? It means there is no such thing as being genetically British because as Mark Thomas says in this Guardian article everyone is related to whichever ethnic group you choose to be related to. What we find instead is that Britain and the UK is a cultural, ethnic and genetic mix, just as any other country in the world that has experienced many migrations since humans left Africa. We do not need ancestry testing to know that we are all related despite all this diversity. What we need to do is celebrate diversity and respect each other, and this is why we need to fight racism, so promote unity, tolerance and remember be a #proudcitizenoftheworld!

 

For more information on genetic ancestry testing see:

http://archive.senseaboutscience.org/pages/genetic-ancestry-testing.html

https://www.ucl.ac.uk/mace-lab/debunking/understanding-testing

 

Danae Dodge

I received my PhD in Scientific Archaeology from the University of Sheffield in 2011 which specialised in ancient DNA and anthropology. For my profile, see my websites: http://independent.academia.edu/DanaeDodge https://www.linkedin.com/pub/danae-dodge/9b/868/389 I started getting involved in Science Brainwaves as a volunteer in 2010. I have volunteered at presentations, events (such as the British Science Festival in 2011) and even participated in the Science is Vital protest march in October 2010. My first blog for Science Brainwaves was "Ancient Humans: Who were they? And who got it on?" which was the written version of a talk I gave for the Natural History Society at the University of Sheffield on 5 December 2011. I also have a public engagement page dedicated to ancient DNA, which I encourage both the public and specialists to join: https://plus.google.com/communities/115424956261446503473