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  • Paige Nelson

DNA Testing – Common Misconceptions

Understanding the limitations of DNA is vital during all aspects of DNA testing, including reviewing results, drawing conclusions, and writing about results or sharing them. DNA is a powerful tool for genealogists however DNA is not magic. As with other records such as a Census or Deeds, DNA Testing cannot give you all the answers to your genealogical questions. Here are some of the most common misconceptions of DNA testing.


1. Genetic Genealogy is only for fun – A genealogist should examine every possible record that can shed light on a genealogical question. Accordingly, a genealogist should use DNA testing whenever it may shed light on a question or whenever it can support or disprove an existing conclusion or hypothesis. DNA testing is a form of evidence, just like any tax records, land record, or census record, that should be evaluated as a potential tool for every research question.

2. Females cannot take a genetic genealogy test – Contrary to popular belief, women can take 3 out the 4 major genetic tests, and both females and males genealogists can benefit from the results of all 4 major tests. This misconception is due to technical limitations in early genetic genealogy. Further, there is no limitation on who may take which test. Each test can provide information about male or female ancestors.

3. DNA Testing will provide a Family Tree – A DNA test alone does not provide a family tree. Instead the test taker is usually given two categories of information: A list of genetic matches who share one or more segments of DNA with the test taker and an ethnicity prediction. A genetic genealogy test can sometimes make it easier to find an existing family tree. Like most genealogical research, DNA testing cannot reach full potential without documentary research that the test taker or their genetic matches have performed on their family tree.

4. DNA results are too narrow to be useful – This misconception is commonly mentioned in news articles writing about genealogy testing. However, authors of these articles usually fail to understand how every test examines many different lines of the family tree.

5. DNA testing will reveal Health Information – This is a quite common misconception and does have some truth. There is no question that a genetic genealogy test can reveal health information about the test taker. However, scientists have discovered that the correlation between health and genetics is complex and that the environment plays a larger role in determining our health. With a rare exception of individuals with serious genetic diseases that have been previously diagnosed before a genetic genealogy test. Most of the major genetic testing companies intentionally do not test for health or erase the information they find from the test results.

6. Genetic genealogy is useless with deceased ancestors – The ability to test parents and grandparents is invaluable, however it is not necessary to successfully use DNA. The DNA that you carry today, which is inherited from your parents and grandparents, can be used to assist in your studying your genetic family tree. At times you may need to have other relatives tested to gain the answer you seek. The more family members you test the easier it usually is to make breakthroughs and discoveries.

7. Genetic genealogy testing is a violation of privacy – There are many people who choose not to take a genetic genealogy test because they are worried that the results could be accessed by people or companies that are not the testing facilities. While it is true that a person does lose some control over their DNA sample after it is sent away, the testing facilities go to great lengths to protect the genetic information in their databases. Many of the concerns you may have about the privacy of your information is unnecessary as you are unlikely to face negative consequences from your DNA information.

8. I should share the same atDNA with my one of my parents or siblings – It is easy to believe that you share all of your parents or siblings matches however the answer depends on the genealogical relationship. The likelihood of sharing DNA with genealogical relatives is very low for distant matches and very high for close matches. Your genetic family tree and your sibling’s genetic family tree will only be partially overlapping, your sibling will have some ancestors in their genetic family tree that you do not have and vice versa.

9. I should share DNA with genealogical relatives – Many test takers who purchase a DNA test expect to receive a list of all their genealogical relatives who have also taken the DNA test. However, because each generation passes down only 50 percent of the DNA to the next generation you will fail to match most of your genealogical cousins, including beyond around the 4th cousin level. In order to share DNA with genealogical relatives, ALL of the following conditions must be met: You inherited DNA from a certain ancestor, your genealogical cousin inherited at least some of the same DNA from the same ancestor, or you and your genealogical cousin inherited some of the same DNA from the same ancestor.

10. The Ethnicity estimate from the testing company should match my genealogy – This is one the biggest misconceptions and one of the biggest complaints from test takers. An ethnicity estimate is simply an estimate and should not be considered a final determination as testing companies are constantly adding to their reference populations. It is impossible to predict a person’s ethnicity due to the limited knowledge some people have about their genetic family tree. The test taker cannot predict which ancestor’s ethnicities may be detected as such little DNA is passed down generation after generation.

11. The relationship prediction given by the testing company is accurate – The relationship predictions usually are a range of possible relationships not an exact relationship prediction. Every genetic genealogy testing company has a slightly different relationship prediction. Similar relationships can result in similar amounts of DNA being shared by genetic matches that complicate relationship predictions. The testing companies cannot guarantee that the prediction is the exact genealogical relationship.


Even with these misconceptions and limitations genetic genealogy can be an exciting and informative addition to genealogical research that can be used to answer specific genealogical mysteries.

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