MyWhy Do Ancient DNA Ancestry Percentages Change Over Time?
It's a common moment of confusion: you log back into a DNA testing account months or years later and your ancestry breakdown looks different, sometimes noticeably so — without you ever submitting a new sample. This is expected behavior, not an error, and it happens for a specific set of reasons.
| Does your DNA data change? | No — your underlying raw DNA data is fixed at the time of testing and never changes |
|---|---|
| What actually changes | The reference panel and statistical model the provider compares your DNA against |
| How often updates happen | Varies by provider — some update reference panels and re-run estimates every year or two, others less predictably |
| Which results shift the most | Smaller percentages and trace-level results are typically the most volatile between updates |
Your DNA doesn't change — the comparison does
Ancestry and ancient-origins percentages are not a direct readout of your DNA; they're the output of a statistical comparison between your DNA and a reference panel of other genomes. When a provider adds more reference samples, refines its reference population boundaries, or improves its comparison algorithm, the same underlying DNA data can produce a different — usually more precise — result the next time it's calculated.
Three main drivers of a percentage change
- Larger reference panels. As providers sequence and add more ancient and modern reference samples, comparisons become more precise, which can shift percentages, especially for smaller components of your results.
- Refined population definitions. A broad reference category can later be split into more specific sub-populations as more data becomes available, changing how your DNA maps onto the new, narrower categories.
- Algorithm improvements. The statistical methods used to assign segments of your DNA to reference populations are actively researched and periodically improved, independent of the reference data itself.
Why this is more common with ancient-origins results specifically
Ancient population genetics is a fast-moving research field — new ancient genomes are published regularly, and each one can refine scientists' understanding of a given ancient population. Because ancient-origins features are often built directly on top of this academic research, they tend to see more frequent and sometimes larger updates than standard modern ethnicity estimates, which rely on more stable reference data.
What this means for interpreting your results
Treat any single ancestry percentage — ancient or modern — as the best available estimate at that moment, not a permanent, fixed fact. Large, well-supported components of your ancestry tend to stay relatively stable across updates, while small or trace-level percentages are the most likely to shift meaningfully. For more on that specific case, see our guide to what "trace" ancestry results mean.
For the underlying mechanics of how these comparisons are built in the first place, see our ancient DNA explainer. If you're comparing how different providers handle this, our DNA ancestry provider comparison covers how frequently each one updates its ancient-origins panel.
Do I need to retest my DNA to get an updated ancestry breakdown?
No. Your raw DNA data doesn't change, so providers recalculate your results against their updated reference panel automatically. You don't need to submit a new sample or pay for a retest to see an updated breakdown.
Does a percentage change mean the earlier result was wrong?
Not necessarily wrong — more accurately, less precise. Both the earlier and later estimates were the best available statistical read at the time, given the reference data available. Updates generally reflect improved precision rather than a correction of an error.