A DNA test can tell you where your ancestors came from, whether you carry genetic variants linked to certain diseases, how your body processes specific medications, and whether you could pass inherited conditions to your children. The exact results depend on which test you buy, but most consumer kits fall into a few core categories: ancestry, health risk, carrier status, drug response, and physical traits.
Ancestry and Ethnic Origins
Ancestry reports break your DNA into percentage-based estimates showing which modern populations you share genetic material with. Most services compare your DNA against more than 200 reference populations from around the world, then display the results as a map or pie chart showing, for example, that you’re 42% West African, 35% Northern European, and 23% East Asian. These numbers are estimates, not exact measurements, and they can shift slightly as companies update their reference databases.
Beyond the ethnicity breakdown, many tests trace your maternal and paternal lineages through two specific pieces of DNA. Your mitochondrial DNA passes from mother to child and reveals your maternal haplogroup, a deep ancestral line stretching back tens of thousands of years. Y-chromosome DNA (available only to biological males) does the same for your paternal line. Haplogroups map the migration routes your ancestors followed across continents, connecting you to broad historical movements rather than specific countries.
Most ancestry services also match you with other customers who share enough DNA to be biological relatives. These matches can range from close family members to distant cousins, which is why people frequently use DNA tests to find birth parents, half-siblings, or previously unknown branches of their family tree.
Genetic Health Risks
Some consumer DNA tests report on genetic variants associated with higher risk for specific diseases. The FDA has authorized reports for a defined set of conditions, including late-onset Alzheimer’s disease, Parkinson’s disease, celiac disease, hereditary blood-clotting disorders, and a condition that causes iron overload called hereditary hemochromatosis. For breast and ovarian cancer, the FDA-authorized test checks for three specific variants in the BRCA1 and BRCA2 genes. These three variants are most common in people of Ashkenazi Jewish descent and do not represent the majority of BRCA variants in the general population.
That last point matters. Consumer tests look at a handful of known variants, not the full gene. A result saying “no variants detected” does not mean you have zero genetic risk for breast cancer. It means the specific variants checked weren’t found. Clinical genetic testing ordered by a doctor examines far more of the gene and is the appropriate next step if you have a strong family history.
Carrier Status for Inherited Conditions
Carrier screening tells you whether you carry a recessive gene variant that could affect your future children, even if you show no symptoms yourself. When both parents carry the same recessive variant, each pregnancy carries a 25% chance of the child having the condition.
The most commonly screened conditions include cystic fibrosis, spinal muscular atrophy (a neuromuscular disease that causes progressive muscle weakness), sickle cell disease, and Tay-Sachs disease. Medical guidelines recommend that cystic fibrosis and spinal muscular atrophy screening be offered to all women considering pregnancy or currently pregnant, regardless of ethnicity. Consumer DNA tests can flag carrier status for dozens of conditions at once, making this one of the most practically useful results for people planning families.
How Your Body Processes Medications
Pharmacogenomic testing reveals how your liver enzymes break down certain drugs, which can make medications work better, worse, or dangerously differently from person to person. The FDA maintains a formal table of drug-gene interactions, and the list is long.
A few examples show why this matters. The blood thinner clopidogrel relies on a liver enzyme to become active. People who are poor metabolizers of this enzyme get less antiplatelet effect, potentially raising their cardiovascular risk. Their doctors may choose a different blood thinner entirely. Warfarin, another blood thinner, is affected by variants in three different genes, all of which influence the dose a person needs.
For pain medications, the differences can be life-threatening. People who are ultrarapid metabolizers convert codeine into its active form much faster than normal, which can cause dangerous respiratory depression. On the other end, poor metabolizers barely convert codeine at all, making it ineffective for pain relief. Tramadol follows a similar pattern. Several antidepressants and antipsychotics are also affected: poor metabolizers may build up higher drug levels in their blood, increasing side effects, which often leads doctors to lower the dose or switch medications.
Not every consumer DNA kit includes pharmacogenomic results, so check before purchasing if this is what you’re after. When they do, the results can give your doctor a head start when choosing or adjusting prescriptions.
Physical Traits and Wellness
Many DNA kits include lighter reports on non-medical traits. These cover things like whether you’re genetically predisposed to taste cilantro as soapy, whether you’re likely lactose intolerant, how quickly you metabolize caffeine, and what type of muscle fibers you tend to have. About 25% of people in the United States are “supertasters,” meaning they experience bitter flavors far more intensely due to having more taste buds on their tongue, a trait linked to a specific gene variant. These reports are generally entertaining and occasionally useful, but they describe tendencies rather than certainties. Your environment, diet, and habits shape these traits just as much as your genes do.
What DNA Tests Cannot Tell You
A DNA test cannot diagnose a disease. A positive result for a health risk variant means your statistical likelihood is higher than average, not that you will develop the condition. Other genetic variants the test didn’t check, your lifestyle, your environment, and your family medical history all play a role. A clean result doesn’t guarantee you’re in the clear, either, because consumer tests examine only a subset of known variants within each gene. Disease-causing mutations can be missed entirely.
Accuracy also varies depending on what’s being tested. For the three Ashkenazi Jewish BRCA founder mutations, one study found the false-positive rate of consumer testing was just 0.6%. But for other cancer-related genes outside that well-studied set, the false-positive rate ranged from 38% to nearly 90%. That means a consumer test flagging a variant in a less common cancer gene has a high chance of being wrong. This is why positive results from consumer kits should be confirmed through clinical-grade testing before making any medical decisions.
Consumer tests also lack the interpretive context that comes with clinical genetic counseling. A raw result saying you carry one copy of a risk variant doesn’t tell you how that interacts with the rest of your genome, your age, your sex, or your personal health history. The number on the screen is a starting point, not a conclusion.
Privacy and Who Can Access Your Data
When you spit into a tube and mail it off, your genetic data enters a private company’s database. How that data gets used varies by company. Major services like 23andMe and Ancestry require a warrant or subpoena before sharing genetic data with law enforcement. GEDmatch, a smaller platform used heavily in genealogy, switched to an opt-in model for law enforcement searches after the high-profile Golden State Killer case, and nearly 90% of its profiles became unavailable to investigators as a result. FamilyTreeDNA took the opposite approach, making users opt out if they didn’t want law enforcement access.
The Department of Justice released a policy in 2019 requiring investigators to search the FBI’s own DNA database first before turning to consumer databases, and to identify themselves before running searches. Still, your genetic information is uniquely permanent. You can change a password, but you can’t change your genome. Before testing, it’s worth reading the company’s privacy policy and understanding whether your data could be shared with third parties for research or other purposes, and whether you can delete it later.