Genetic Testing vs Epigenetic Testing
Genetic tests read the DNA sequence; epigenetic tests read chemical marks on DNA. This page compares what each measures, how reliable they are, and what they cannot tell you.
Content last updated . This page has not been medically reviewed.
Definitions
Genetic testing identifies changes in genes, chromosomes or proteins. Gene tests study DNA sequences to find variations that can cause or raise the risk of a genetic condition. [1]Epigenetics is the study of changes in DNA that do not involve alterations to the underlying sequence. The chemical modifications change the degree to which genes are turned on and off. [2] The "off" and "on" wording is a simplification; see Why "Turning Genes On or Off" Is Often an Oversimplification.
The difference at a glance
| Genetic test | Epigenetic test | |
|---|---|---|
| What is read | DNA sequence variants [1] | Chemical marks that regulate genes, for example DNA methylation [2] |
| Established clinical uses | Confirming or ruling out a suspected genetic condition [1] | Not covered by the sources read for this page |
| Main limits | A negative result does not mean no risk; companies test different variants [3] | Technical noise in some clock measurements [4] |
| Regulatory status (US) | Some direct-to-consumer tests are reviewed by the FDA; others are not [3] | Check each test; not verified here |
What genetic tests can and cannot do
A medical genetic test can confirm or rule out a suspected genetic condition or help estimate the chance of developing or passing on a disorder. [1] MedlinePlus suggests a geneticist or genetic counselor can explain pros and cons. [1]For direct-to-consumer tests the FDA says tests for non-medical, general wellness or low-risk medical purposes are generally not reviewed before they are offered. [3] It also says a negative result means a person may still be at risk, and that companies do not all test the same variants, so results for the same condition may differ. [3] Learn more at Direct-to-Consumer Genetic Tests and Genetic Test False Positives and Clinical Confirmation.
What epigenetic tests can and cannot do
Epigenetic clocks are aging estimates calculated from DNA methylation data. One laboratory study found technical noise produced differences of up to 9 years between replicate measurements for six prominent clocks. [4] The same paper proposed a computational fix that improved agreement, which shows the problem was real and also that it may be reduced. [4] A single lab report, then, can carry more uncertainty than its precise-looking number suggests.Evidence label for using epigenetic age results to guide personal health decisions: insufficient evidence from the sources read here. A change in a marker is a biomarker change, not a proven health outcome. See Epigenetic Wellness Tests and Epigenetic Age Tests: Reading the Claims.
Do results change behavior?
A systematic review of 18 trials found no significant effect of telling people their DNA-based disease-risk estimates on smoking cessation, diet or physical activity, with mostly low-quality evidence. [5] That finding concerns genetic risk reports; trials of epigenetic reports were not covered by the sources read.Frequently asked questions
Which test is more accurate?
They measure different things, so accuracy cannot be compared directly. The FDA notes that direct-to-consumer genetic tests vary in the variants they cover, [3] and one study found replicate epigenetic clock readings could differ by years because of technical noise. [4]
Can an epigenetic test tell my real age?
It estimates a "biological age" from DNA methylation. Such estimates can be noisy and are not proven to guide health choices. [4]
Does a negative genetic test mean I am safe?
No. The FDA says a negative result means a person may still be at risk. [3]
Do these tests change what people do?
A review of trials found no significant effect of genetic risk information on smoking, diet or activity. [5]
Can I use a home test to diagnose a condition?
A consumer test result is not by itself a diagnosis. The FDA suggests discussing results with a genetic counselor or qualified health care provider. [3]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Practical cautions
- A test result is not a diagnosis. Take surprising results to a clinician or genetic counselor.
- Genetic results can raise privacy questions and unexpected findings; see Genetic Privacy and Incidental Findings.
- Do not change medicines or start treatments based on a wellness report.
References
- MedlinePlus Genetics, What is genetic testing?. Read 2026-10-22.
- NHGRI, Talking Glossary: Epigenetics. Read 2026-10-22.
- FDA, Direct-to-Consumer Tests. Read 2026-10-22.
- Reliability of epigenetic clocks, Nature Aging 2022 (PubMed 36277076). Read 2026-10-22.
- Systematic review: communicating genetic risks and behaviour, BMJ 2016 (PubMed 26979548). Read 2026-10-22.