Digging out some of the truth about DNA testing for ethnicity
If someone or some company offers you to do DNA testing for ethnicity then surprise and curiosity, probably, would be the reaction of most people. After all, would it not be amazing to find out by analysing your DNA so many exact things such as ethnicity, family members, ancestors and illness predispositions? Any mildly curious person would be happy to get their hands on this. However, at the level of the technology we have today, you have to be a little bit careful and aware of what the limitations of these analysis are.
They are not entirely accurate. For example, the famous Oprah Winfrey had her DNA testing done and the results were read to her on her TV show. The company which tested the results told her that her ancestors came from Africa and that they were from the Zulu tribe. That sounds like a lot of fun, but the problem is that no Zulu were ever captured and brought to the United States as slaves. So if that’s the case then she can’t possibly be descended from the Zulu tribe.
Furthermore, it is not entirely true that DNA testing for ethnicity will actually give results of ethnicity. They are not able to give many details at all. As a matter of fact they are completely not able to say what region or tribe or group of people one comes from. They are only able to make a breakdown by broad groups such as European, African, Asian, and Native American.
With DNA testing they can make accurate analysis up to 5 generations back how closely people are related, but again, it is important to understand what this means. They use a large sample of DNA and they start looking at similarities between brothers, then between cousins and so on, farther and farther. Then, they analyse the statistics and they say that up to 5 generations back, there is a high likelihood of the correct matching. However, the percentage itself is only 20% on level 5 and this could truly mean that there is a relation between you and this person or it could mean that there is another person who has 20% similar DNA as you. So you see, it is much more of an indication or a guide for you to go and further investigate (real life detective style) and so the results should not be taken as facts. But that said, if you are adopted or have lost contact with your family this method could give you some answers or places to start looking.
DNA testing for ethnicity: issue with the database size
Looking deeper into the limitations of the testing we find that the DNA results are understood only in relation to other DNA results. That means that the accuracy of results is highly dependent on the size of the database of the company which is offering you the DNA testing for ethnicity. And as time goes by there are more and more companies multiplying extremely fast trying to catch a portion of this lucrative business, so it is important for anyone paying this large amount of money (starting from $100 and going up a lot) to understand that a lot of companies out there are just in it to sell you some general useless information and take your money. Especially the less known and younger companies would have very limited databases and so just by the limitation of their sample size they would have a poor accuracy in testing.
DNA testing for ethnicity: issue with comparing test results
Furthermore test results are not even the same, i.e. if you have your DNA tested for ethnicity at several companies (without telling each of them) and then compare the results, then there is a high chance that the results will not match! Of course this will cost a lot more than the already large sum required for 1 test, but this is a simple and sure way to prove that the testing is not just inaccurate, it is simply invalid. It is important to understand that DNA testing for genealogy is a very important tool for scientists, but unfortunately, as some people and companies have understood that they can sell nonsensical results to the general public, it has gone a little bit the wrong way and there is no regulation at all on this by any government or law.