Genetics researchers say that commercial DNA tests cannot provide accurate stories about personal ancestry. Part of a rapidly growing market for genealogy, 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.
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Comets and the Horns of Moses