Ageing research
Biological-age tests: what a younger score really means
A report that says you are biologically younger can feel rewarding. But a lower score is not, on its own, proof that you will live longer or that your new supplement worked. Before paying for repeated tests, find out what the test is estimating.
Different questions can produce different clocks
An epigenetic clock uses patterns of DNA methylation to estimate age or an ageing-related measure. A September 2026 preprint examined selected methylation sites from 13 published clocks and asked how inherited genetic variation might influence those inputs. [1]
A chronological-age estimate, a risk-associated measure and a proposed pace-of-ageing measure are different targets. Ask the testing company to name the model and explain the result in terms of its actual target. The word 'age' on the front page does not settle that question.
What the September preprint adds
The GIA preprint, posted on 15 September, reports that methylation sites used in those clocks were enriched for sites linked to inherited genetic variation. The author argues that some differences between people's clock results may reflect inherited differences, alongside ageing-related change. [1]
This is exploratory research, not a clinical verdict on every commercial test. It does not show that all biological-age scores are useless or explain any particular person's result. Direct testing of the proposed relationships remains important. We are not treating a preprint as settled medical guidance. [1]
Questions before a repeat purchase
Ask how much the score typically varies when the same sample is measured again. Then ask about variation between samples, the population used to develop the model and whether the company has changed its algorithm since your last test.
If a seller says your score improved, request the uncertainty around that change. If they attribute it to a product, ask for a study that tests that causal claim. Two readings taken at different times are not automatically such a study.
The FDA explains that consumer tests vary in their supporting evidence. Its guidance distinguishes measuring something reliably from showing that the measurement predicts a state of health. [2]
Keep the report in proportion
Before buying, write down what decision would change after the result and who would help interpret it. If the plan is only to buy more tests until the number looks better, pause and reconsider what you want from the process.
Discuss medical concerns with a qualified professional. DomDNA's lifestyle quiz does not measure DNA methylation, calculate biological age or verify anti-ageing treatments. You can explore the topic without submitting a DNA file or buying a longevity stack.