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What to Know Before Buying a Home DNA Test

illustration showing a hand reaching out to a dna double helix

A wealth of information is hidden in the DNA inside our cells – information that can tell us more about the parents, grandparents, and older ancestors who passed down their DNA to us – and information that can tell us more about ourselves. This genetic information can include inherited traits such as eye color and height. It can include possible links to medical conditions such as high cholesterol or sickle cell anemia. It can also include gene changes that may lead to a higher risk for diseases such as cancer.

Companies that sell home DNA testing services – including 23andMe, Ancestry, and Family Tree – offer to analyze your DNA from a saliva sample and tell you where your ancestors likely lived and allow you to compare your results with others in a database to look for relatives. You can also opt to learn about certain genetic health risks and whether you are a carrier for certain inherited conditions.

Scientific experts say it may be best to use these services purely for entertainment value. Results of geographic ancestry percentages are based on probabilities, which means they may have a wide margin of error. For example, they are better at predicting the continent your ancestors came from than the country. And while it may seem intriguing to learn of a long-lost relative, you may risk getting misinformation or accidentally unearthing a sensitive family issue. Using at-home tests to learn about medical risk factors can also be difficult to understand, and may create problems you didn’t expect.

The FDA’s role

The FDA cautions that direct-to-consumer tests may provide incorrect or misleading information, and advises talking to a medical professional before using the results to make any health choices.

Because of this, the US Food and Drug Administration (FDA) places some restrictions on genetic health risk testing sold directly to consumers. The FDA cautions that direct-to-consumer tests may provide incorrect or misleading information, and advises talking to a medical professional before using the results to make any health choices. Even so, the FDA last November announced plans to streamline review of genetic health risk tests, which will make it easier for companies to market and sell their products.

That announcement was the FDA’s latest action concerning genetic test developers. In 2013, the agency warned 23andMe about selling its health testing services without first getting FDA clearance. In response, 23andMe began providing customers who purchased the tests with only raw data, and no analysis. Customers had to purchase the services of a different company to make sense of this data. In April 2017, the FDA gave 23andMe approval to sell tests for 10 health risks, including Parkinson’s disease, celiac disease, and late-onset Alzheimer’s. Results inform customers whether they have one of the genetic variants tested for by 23andMe. They advise customers with concerns about their results to speak to a healthcare professional.

The streamlined review process could help other companies compete with 23andMe.

Experts advise caution

Genetics experts caution about diving into your genetic history without first doing your homework. We talked to Christine Stanislaw, M.S., CGC, Director of Genetic Counseling, Winship Cancer Institute of Emory University.

Q. Are the results of direct-to-consumer genetic health risk tests accurate?

A. The methods used by these testing services are a less specific way of analyzing DNA than you would receive in a certified laboratory, which adheres to federal standards, and is less likely to be able to predict your chances of developing a health problem. Results that come in the form of raw data must be analyzed by a third party for an additional fee. Inaccurate interpretation of the data by these companies has been reported and could result in a false positive result.

Q. Why does a false positive result matter?

A.  A false positive occurs when the third-party interpretation finds a DNA change (mutation) that they associate with a health risk, but re-testing in a certified clinical laboratory either does not confirm the DNA change or, based on scientific data, determines that the change is not linked to a health risk. False positive results can create confusion and anxiety. When people are re-tested in a medical setting and learn they do not have increased risk, they may feel relief. But re-testing may not be covered by health insurance and sometimes people feel they’ve wasted time and money.

Q. If you take a test and the results indicate you’re at risk for a health problem, what should be your next step?

A. If you receive concerning results that indicate cancer risk or other risk from an associated gene mutation, the next step is to make an appointment with a genetic counselor. If you want diagnostic information that can tell you what actions to take, you should have a clinical test in a medical setting that involves full analysis of the relevant genes, and interpretation of test results by a genetics professional.

Q. What kind of health actions are possible for people who learn they have a genetic risk for cancer or other disease?

A. In some cases, people can be screened at an earlier age or screened more frequently than people who are at average risk. Other options for risk reduction include preventive surgeries or medications. Even in cases when tools for screening are not available, there is benefit to early knowledge because it lowers the threshold for investigating signs or symptoms. And for some people and families, having an explanation can provide peace of mind.

Q. What do you tell your friends who ask you whether direct-to-consumer genetic health risk testing is a good idea?

A. I tell my friends if they want to get tested just for fun, that’s great, but I caution them against using results to alter their lifestyle or make assumptions related to health risks. Family health history is still the better tool for predicting health risks.

Who should consider genetic counseling for cancer risk?

If you’re thinking of getting genetic testing, first talk to your health care provider and plan to meet with a genetic counselor. This will help you know what to expect. The counselor can tell you about the pros and cons of the test, what the results might mean, and the best testing options available based on your family history.

Genetic counseling and testing may be recommended for people who have had certain cancers or certain patterns of cancer in their family. If you have any of the following, you might consider genetic testing:

  • Several first-degree relatives (mother, father, sisters, brothers, children) with cancer
  • Many relatives on one side of the family who have had the same type of cancer
  • A cluster of cancers in your family that are known to be linked to a single gene mutation (such as breast, ovarian, and pancreatic cancers in your family).
  • A family member with more than 1 type of cancer
  • Family members who had cancer at a younger age than normal for that type of cancer
  • Close relatives with cancers that are linked to rare hereditary cancer syndromes
  • A family member with a rare cancer, such as breast cancer in a male or retinoblastoma
  • Ethnicity (for example, Ashkenazi Jewish ancestry is linked to hereditary ovarian and breast cancers)
  • A physical finding that’s linked to an inherited cancer (such as having many colon polyps)
  • A known genetic mutation in one or more family members who have already had genetic testing

Genetic testing recommended by a genetics expert can tell you if you have a specific gene mutation that raises your risk of developing cancer, but it can’t tell you whether you will or will not develop cancer. And not all gene changes are problematic. It may not yet be known if some mutations are harmless or if they increase certain health risks. Researchers are always learning more about the results of genetic testing and what they might mean, but at this time there are still many unanswered questions. 

The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.