Direct-to-consumer genetic testing can provide interesting information about your health, traits, and ancestry. However, the results may not be clear-cut. Companies that provide these tests often tell their customers that the results are for information, education, and research purposes only—they are not meant to diagnose, prevent, or treat any disease or health condition. It is useful to keep this distinction in mind when interpreting your own test results.
Health and disease risk
The results of these genetic tests provide information about your chance of developing certain diseases (such as celiac disease or Parkinson's disease) and the likelihood that you have particular traits (such as dimples or lactose intolerance). These tests may also provide information about how a person may respond to certain drugs (pharmacogenomics). Test results are usually based on an analysis of one or more genetic variations that are known or suspected to be associated with the disease or trait. Direct-to-consumer genetic tests do not look at all genetic variants associated with diseases or traits.
The results of tests to predict disease risk do not provide a “yes or no” answer about whether a person will develop a given disease. Other factors, including genetic variations that were not tested, environmental factors, and lifestyle choices (such as diet and exercise) also contribute to disease risk in ways that may not be fully understood. Therefore, a result showing an increased risk does not mean you will definitely develop the disease, and a result showing a reduced risk does not mean you will never develop the disease.
Ancestry or genealogy
The results of these tests give clues about major geographic areas that are your family’s origins. These results are calculated on the basis of genetic variations that are more common in people from certain areas of the world than in others.
Sometimes the results of ancestry testing are unexpected or inconsistent with what a person understands about his or her family history. People who are closely related, such as siblings, may receive slightly different information about their ancestry because results are limited by the number and diversity of people who have submitted DNA samples to a given direct-to-consumer genetic testing company. It is important to be aware that receiving unexpected or ambiguous information about your background is a potential risk with this type of testing.
The results of these tests give information about individuals who are likely related to you. (These individuals have also undergone testing, and the predictions are based on similarities among DNA sequences.) These tests can uncover previously unknown information about biological relationships among people (such as paternity). It is important to be aware that receiving unexpected or ambiguous information about your background or family is a potential risk with this type of testing.
In most cases, direct-to-consumer lifestyle tests assess genetic variations related to very specific traits, such as how your body converts the nutrients from food into energy (metabolism), day/night (circadian) rhythm, or the senses of taste and smell. The company may recommend specific diet or fitness programs, dietary supplements, skincare products, or other products and services on the basis of your results. However, in most cases the link between a given genetic variation and a complex trait like weight, athletic performance, or sleep is indirect or unknown. Therefore, the results of these tests can be challenging to interpret, and it can be difficult to predict whether a recommended product or service will be helpful to you.
If you have questions about the meaning of your test results, professional support (such as guidance from a genetic counselor) may be available from the company that provided the test. You can also share questions about your results with your own healthcare provider. Talk to your doctor before making any major changes in managing your health, diet, or fitness after you receive results of a direct-to-consumer genetic test.