10 DNA Testing Myths Busted
Posted by Blaine Bettinger, Ph.D.
(c) 25 October 2007
1. Genetic genealogy is only for hardcore genealogists. Wrong! If you’ve ever wondered about the origins of your DNA, or about your direct paternal or maternal ancestral line, then genetic genealogy might be an interesting way to learn more. Although DNA testing of a single line, such as through an mtDNA test, will only examine one ancestor out of 1024 potential ancestors at 10 generations ago, this is a 100% improvement over 0 ancestors out of 1024. If you add your father’s Y-DNA, this is a 200% improvement. Now add your mother’s mtDNA, and so on. However, with this in mind, please note the next myth:
2. I’m going to send in my DNA sample and get back my entire family tree. Sorry. DNA alone cannot tell a person who their great-grandmother was, or what Italian village their great-great grandfather came from. Genetic genealogy can be an informative and exciting addition to traditional research, and can sometimes be used to answer specific genealogical mysteries.
3. I would like to try genetic genealogy, but I’m terrified of needles. Good news! Genetic genealogy firms don’t use blood samples to collect cells for DNA testing. Instead, these companies send swabs or other means to gently obtain cells from the cheek and saliva.
4. I would like to test my ancestor’s DNA, but they died years ago. You don’t always need your ancestor’s DNA to get useful information from a genetic genealogy test. If you are male, you contain the Y-chromosome (Y-DNA) that was given to you by your father, who received it from his father, and so on. Both males and females have mitochondrial DNA (mtDNA), which was passed on to them by their mother, who received it from her mother, and so on. Everyone of us contains DNA (Y-DNA and/or mtDNA) from our ancestors that can be studied by genetic genealogy.
5. I want to test my mother’s father’s Y-DNA, but since he didn’t pass on his Y-chromosome to my mother, I’m out of luck. Wrong! There is a very good chance that there is another source of that same Y-DNA. For instance, does your mother have a brother (your uncle) who inherited the Y-DNA from his father? Or does your mother’s father have a brother (your great-uncle) who would be willing to submit DNA for the test? Sometimes there might not be an obvious source of “lost” Y-DNA, or no one in the family is willing to take a DNA test. The secret to solving this problem is to do what every good genealogist does – use traditional genealogical research (paper records, census information, etc) to “trace the DNA”. Follow the line back while tracing descendants in order to find someone who is interested in learning more about their Y-DNA. This applies to finding a source of mtDNA as well.
6. Only men can submit DNA for genetic genealogy tests, since women do not have the Y-chromosome. Wrong! Most genetic genealogy testing companies also offer mtDNA testing. Both men and women have mtDNA in their cells and can submit that DNA for testing. In addition, women can test their father’s, brother’s, or some other male relative’s Y-DNA to learn more about their paternal ancestral line, even though they did not inherit the Y-chromosome.
7. My genetic genealogy test will also reveal my propensity for diseases associated with the Y-chromosome and mtDNA. Wrong, thank goodness. Most of the information obtained by genetic genealogy tests has no known medical relevancy, and these firms are not actively looking for medical information. It is important to note, however, that some medical information (such as infertility detected by DYS464 testing or other diseases detectable by a full mtDNA sequence) might inadvertently be revealed by a genetic genealogy test.
8. I don’t like the thought of a company having my DNA on file or my losing control over my DNA sample. This is, of course, an understandable concern. However, most testing firms give a client two options: the DNA is either immediately destroyed once the tests are run, or it is securely stored for future testing. If the DNA is stored, the firm will typically destroy the DNA upon request. If the long-term storage of DNA is a concern, be sure to research the company’s policy before sending in a sample.
9. If my test reveals Native American ancestry, I plan to join a particular Native American affiliation group. Although genetic genealogy can potentially reveal Native American ancestry (for instance, my mtDNA belongs to the Native American haplogroup A2), it is incredibly unlikely that this information will be sufficient to positively identify the specific source of the lineage (such as a tribe) or allow membership in a particular Native American affiliation.
10. My DNA is so boring that genetic genealogy would be a waste of time and money. Very wrong! A person’s DNA is a very special possession – although everyone has DNA, everyone’s DNA is different (okay, except identical twins – if your identical twin has been tested, you should think twice about buying the same test!). As humans settled the world, Y-DNA and mtDNA spread and mixed randomly. As a result, it is impossible to guess with 100% assurance that a person’s Y-DNA or mtDNA belongs to a particular haplogroup (a related family of DNA sequences) without DNA testing.
BONUS MYTH: My genetic genealogy test says that my mtDNA belongs to Haplogroup A2. Juanita the Ice Maiden, a frozen mummy discovered in the Andes Mountains in Peru also has Haplogroup A2 mtDNA. Therefore, she must be my ancestor!
Unfortunately, although genetic genealogy can reveal that a person is RELATED to an ancient DNA source, it cannot prove that a person is a DESCENDANT of an ancient DNA source. For instance, perhaps you are descended from Juanita’s sister, or her 5th cousin. Thus, although Juanita might be your great-great-great-great…great-grandmother, she might instead be your great-great-great-great…great-aunt. And since Juanita died when she was just 12 to 14, it is unlikely she has any descendants.
If you understand the risks associated with genetic genealogy (such as the detection of non-paternal events and other risks) and are ready and willing to embrace the results to learn more about your genetic ancestry, then genetic genealogy might be for you. I recommend that you read archived posts here at The Genetic Genealogist, and do some online research through one of the many companies that offer genetic genealogy testing.