DNA Testing and Your Ethnicity

TV ads are making DNA test kits a favorite gift idea for adults. These are autosomal (atDNA) kits that give two types of results: ethnicity percentages and individual matches. Most of the test-takers of these gift test kits seem to be only interested in the ethnicity percentages. I feel this is true because I see that over half of my individual matches have no family trees and a reluctance to respond to my contacts. No one has responded when a family tree is not attached.

However, the ethnicity estimates that test companies supply may be confusing due to limitations in the way the testing companies calculate the ethnicity estimates. In fact, the projected ethnicities are not foolproof; they are estimates based on the comparison of the test sample to a reference population used by the testing company. The companies then used their algorithms to determine the percentage of each ethnic group you belong to you.

Are these projections reliable? Initially, some people complained that their ethnic estimates were inaccurate. Each test company has different reference populations, and these numbers cause more confusion because the ethnic percentages will differ from different companies. However, this is a relatively new science, and companies are revising their methods and base data regularly.

The testing companies regularly add DNA from new individuals and more population segments to the reference panels. Recently, they changed many ethnic estimates that now seem more accurate. The results from companies still vary when compared to other companies, and will likely continue to improve as they add more individual samples from more comprehensive geographical locations and sources. Eventually, I believe the projected ethnicities from each company will become closer to being similar.

The size and the populations in the reference panel are substantial factors determining the accuracy of an ethnicity projection. If the reference population does not include a segment of the world’s population such as Native Hawaiians, the ethnicity estimate cannot have that as one of the results, even if the test-taker has significant ancestry from that part of the world. Each testing company describes their reference populations in the help or information sections of their websites.

There are limitations as to how much detail the projected ethnicities can show due to the widespread migrations of different people across the different continents. One example of this is the population of central and western Europe. DNA between Germany and France to predict which country your ancestors left accurately. Another example is the populations in southern Europe along the coast of the Mediterranean Sea. There are no significant differences in the

The estimated ethnicity for broad categories such as Asia, Africa, Europe, and the Americas are generally accurate, but the accuracy decreases when the projection tries to be more specific as to location or country.

Another limitation in determining a person’s ethnicity arises from the fact that the person may not have received any DNA from their ancestors from a particular region. We lose portions of DNA for older generations as each generation gets DNA from their parents. The amount of DNA from each ancestor in older generations until the piece left is so small that it may not be passed along to the next generation. This scenario may completely eliminate DNA from a geographic location.

Ethnicity seems to be one of the top reasons why people are submitting DNA samples. They want to know where are their roots. However, the results are only an estimate and have severe limitations. Be cautious when evaluating and using your ethnicity results, especially if you are looking for clues to specific locations or countries. Use the results as clues and be patient because the results will be revised many times in the future.


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