DNA, Ancestry Testing and You
The DNA in your body is 99.9 percent identical to 99.9 percent of other people’s DNA. What about the other 0.1 percent? Variations in this tiny portion of our DNA explain why individuals have different health risks, resemble relatives and can sometimes be identified as belonging to particular ethnic groups.
“Ancestry testing” is a category of DNA testing that has grown in popularity in recent years. People order this type of at-home DNA testing to answer questions like: “Where did my ancestors originate?” and “Can I find relatives using DNA testing?” Many people are interested in answering both of these questions.
Because DNA is a history book of our genetic past, results of DNA testing can solve mysteries and satisfy curiosity. Some use the testing to track down a biological parent or locate half-siblings they know are out there somewhere. But the testing can also reveal surprises – some pleasant, some not so. People discover unexpected ethnicity or unknown relatives. Others learn they were conceived using donor sperm or were born of incest and not told by their parents.
Most of the time, an individual tester is not confronted with these surprises, but because so many of these tests are being ordered, unexpected outcomes happen on a regular basis. If you consider ancestry testing, think ahead about how you might react to and use the information, and how this information might affect your family. It is also important to think ahead about your goals for testing so that you can choose a test that fits your needs. Genetic counselors can help.
Here are some common questions to ask if you’re considering ancestry testing:
How does ancestry testing identify ethnicity?
The finding of particular markers in your DNA can indicate you belong to certain ethnic populations from around the world. Most people find out they have a variety of ethnic backgrounds. This isn’t an exact science so it’s important to know your results can vary.
How does ancestry testing identify biological relatives?
Segments of your DNA can be compared against the DNA of other people in the same database, and if there is an identical “match,” you likely share at least one ancestor, like a great-grandparent. The companies offering the test for autosomal testing have databases of testers that grow larger by the day. If you match someone and both agree to be connected, you can communicate with one another using social networking features or via email.
If I am an adoptee, what can ancestry testing do for me?
Keep in mind that the process of finding a relative through DNA testing may be the easy part; preparing yourself for how the information may affect you and other family members may be more complicated. Genetic counselors can help you understand how to use your test results to protect your health.Genetic counselors understand the potential uses and the value of DNA testing to help answer questions for adoptees. As ancestry databases grow over time to include more people, the usefulness of these DNA databases will increase for adoptees seeking biological relatives. Keep in mind that the process of finding a relative through DNA testing may be the easy part; preparing yourself for how the information may affect you and other family members may be more complicated. Genetic counselors can help you understand how to use your test results to protect your health.
Can ancestry testing results tell me about my risks for health conditions?
Many of the genetic markers analyzed for ancestry reasons don’t have anything to do with health, but some of them do. This information can be interpreted into health risk data to those who know how to do it, by downloading the test’s “raw data” (a computer file of the genetic letters seen at all the different locations tested). Some testers are doing this with their ancestry results: they download the raw data and analyze their markers for certain health risks, using special computer software they can find and access online. The information from these third-party tools should be considered incomplete and not to be relied on for health reasons. Ancestry testing only looks at a fraction of the total DNA a person carries.
Will I get health information back from an ancestry company?
For a period of time before the FDA got involved, some DNA testing companies told customers their DNA health risks directly, without having a doctor or other provider involved in ordering the test or returning the results. For now, you can download your raw data from a few ancestry testing companies, but companies won’t tell you anything about your health risks.
If you connect with relatives using ancestry testing, and they choose to share health information with you, you may find out additional family health history you never knew about. Consider speaking with a genetic counselor to discuss your family health history if this happens to you, especially if there are conditions with strong genetic risks, like Huntington’s disease or early-onset breast and ovarian cancer.
Should I have an at-home DNA test to learn more about my ethnic background or to search for DNA relatives?
There is no simple answer to this question. Every person will have different reasons for undergoing ancestry testing and have individual reactions to the results. Before you test, ask questions like these:
- What testing is available, and what it will tell me?
- Will the testing company share my DNA information with anyone else, like a pharmaceutical company or researchers?
- Where can I turn for help if I have questions or need support after my testing?
Understanding DNA and genetic testing can be overwhelming at first, but there are resources available for those who want to learn more. If you are interested in meeting with or speaking to a genetic counselor, you can find one in your area using NSGC’s “Find a Genetic Counselor” tool.
For NSGC members interested in learning more about ancestry testing, log in to the “members only” section and watch the webinar “What GCs Need to Know: Basics of DNA Ancestry and Genetic Genealogy Testing.” You can also find an extended list of Q&As from the webinar presenters and locate a list of resources available for learning more.
Brianne Kirkpatrick, MS, LGC is an NSGC member and a genetic counselor and research coordinator at Geisinger Health System.