Using our reference dataset we compare your DNA to geographical locations to establish percentages.
We may not be able to establish parts of your ancestry if:
- We do not have a reference panel for your population or region of interest.
- We have a low sample size for that population or region.
- There is further population structure within that population or region.
- Any combination of these factors.
It is currently not possible to take a DNA test to determine your percentages from each and every country in the world, and probably never will be.
Due to human mobility, DNA differences do not necessarily correspond with national boundaries; for example, someone from Brittany in France may have more genetic similarity with an English person from Cornwall than with a French person from Marseilles.
In the cases where our fine-scale algorithm cannot distinguish between very genetically similar areas, we group them into genetically-distinct clusters that often reflect natural geographical boundaries. In order to clearly distinguish results in more specific regions, sample data fulfilling very specific criteria will have to be collected and included in our reference datasets. This is a process that takes years.
Many populations are themselves formed from a mixture of other populations. Our algorithm will attempt to match you directly to a population or region that we have in our reference database.