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News and Comment

We are all "related" to Romans, Vikings, Egyptians & Attila the Hun

7 March 2013

Scientists warn the public that some commercial DNA tests are ‘genetic astrology’.

Genetics researchers say that commercial DNA tests cannot provide accurate stories about personal ancestry. Part of a rapidly growing interest in deep ancestry, commercial ‘genetic ancestry tests’ offer people a profile of their genetic history based on a DNA sample for around £200. The test findings tell people that they have links to groups such as Aboriginals or Vikings, to particular migrations of people and sometimes to famous figures such as Napoleon or Cleopatra. But the researchers warn that such histories are either so general as to be personally meaningless or they are just speculation from thin evidence.

They are issuing their warning alongside a public guide, published today: Sense About Genetic Ancestry Testing, where they explain why DNA tests are used in population research and why they do not provide accurate information about an individual’s ancestry:

  • Our individual ancestry is much shallower than people might imagine – the best estimate is that the most recent person from whom everyone alive today is descended lived just 3,500 years ago.
  • As we look back through time we quickly accumulate more ancestors than we have sections of DNA, which means we have ancestors from whom we have inherited no DNA.
  • There are millions of possible ‘stories’ of your ancestry. To know whether any one of them is likely to be true, it would need to be tested statistically for its likelihood against other possibilities.
  • The genetic ancestry business uses a phenomenon well-known in other areas such as horoscopes, where general information is interpreted as being more personal than it really is.

Comments

David Balding, Professor of Statistical Genetics, UCL Genetics Institute: "Be wary of news items about genetic history - that someone famous is related to the Queen of Sheba or a Roman soldier.  Often these come from PR material provided by genetic testing companies and can be trivial, exaggerated or just plain wrong. Genetic relatedness isn't very meaningful beyond a handful of generations away, because the amount of DNA you share with a very distant relative is negligible compared with the huge amount of DNA we all share from our common ancestors." 

Mark Thomas, Professor of Evolutionary Genetics, Department of Genetics, Evolution and Environment, UCL: "Ancestry is complicated and very messy. Genetics is even messier. The Y chromosome and mitochondrial DNA contain little information about an individual’s ancestry. The idea that we can read our ancestry directly from our genes is absurd. In recent months there has been a spate of newspaper, TV and radio stories about famous people being descended from other famous people, or cool groups like Vikings. But these claims are usually planted by the companies that provide these so-called tests and are not backed up by published scientific research. This is business, and the business is genetic astrology.”

Professor Mark Jobling, Professor of Genetics, University of Leicester: “Over-interpretation is always a pitfall in studies of genetic history, and particularly so when the history is of individuals. Some suppliers of individualised tests have been guilty of telling punters what they want to hear, by spinning implausibly specific stories about ancestry, such as Viking or Celtic origins for their Y chromosome or mitochondrial DNA. Information and demystification is clearly needed.”

Tracey Brown, Director, Sense About Science: “Genetics researchers are telling us that you are better off digging around in your loft than doing a DNA ancestry test if you want to find out about your family tree. We tend to see DNA tests as providing specific personal information, because of their use in crime detection and medical diagnosis. The genetic ancestry business trades on this.” 

Steve Jones, Emeritus Professor of Human Genetics, Evolution & Environment, UCL: “On a long trudge through history – two parents, four great-grandparents, and so on – very soon everyone runs out of ancestors and has to share them. As a result, almost every Briton is a descendant of Viking hordes, Roman legions, African migrants, Indian Brahmins, or anyone else they fancy.” 

Lounes Chikhi, CNRS Senior Scientist (Directeur de Recherche) at the Evolution and Biological Diversity lab, Paul Sabatier University, Toulouse, France: "The interpretation of genetic data is already difficult where geneticists try to reconstruct aspects of our recent evolutionary history, and becomes desperately so when we try to do the same for specific individuals. Unfortunately, many claims made by ancestry companies are closer to ‘folk genetics’ than real population genetics. Everybody wants to be related to Genghis Khan or the Vikings (well I actually don't). The good news is that they all probably are."

Mike Weale, Reader in Statistical Genetics, Department of Medical and Molecular Genetics, KCL: “I know it’s only a tiny part of my true ancestry, but I would still love to know whether my male line ancestors were Vikings, or Celts, or both, or neither. Or at least be reasonably certain. Same goes for my female line. It’s a shame there’s no valid way to do that.”

Turi King, Lecturer in Genetics and Archaeology, University of Leicester: "The services offered by genetic testing companies can be perfectly valid in cases where individuals want to verify genealogical links, such as in surname studies.  However, for deep ancestry testing, what is being done is to extrapolate from the field of population genetics  to individual genetics, often not revealing the problems and grey areas inherent in this. You would need a time machine to be able to go back and find out who a particular ancestor was and what he/she were up to, e.g. whether they were a marauding Viking or a farmer (or both), as genetics alone cannot tell you this. What we can safely say is that we are all related to one another (including any famous person you care to name) and all have Anglo-Saxons, Vikings, Celts, Romans, you name it, in our family trees."

Read the guest blog on Sense About Genealogical DNA Testing by Debbie Kennett, freelance editor and genealogist.


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