Let’s Talk About DNA: Ancestral Regions
What are “Ancestral Regions” and how are they determined?
When you submit your DNA to AncestryDNA (or a similar autosomal test), the company doesn’t simply say “you are Irish” or “you are German.” Instead it gives you a percentage breakdown of the regions where your DNA is most genetically similar to people whose ancestors lived in a particular place. These are called “Ancestral Regions” or “Ethnicity Estimates”.
Here’s how it works in broad brush:
The test analyzes your autosomal DNA (DNA inherited from both parents, across chromosomes 1-22 in hundreds of thousands of locations).
AncestryDNA has built what are called reference populations or reference panels: people whose known family history shows their ancestors remained in a certain region for many generations. The company then compares your DNA to those reference panels, asking: “How similar is your DNA to the DNA typical of people from this region?”
Because DNA segments are inherited randomly, you may share more of the segments typical of region-A versus region-B, and the algorithm translates that into a percentage. For example: “42 % Southeastern England & Northwestern Europe” means that about 42 % of your measured DNA is most similar to reference people whose ancestors lived in that region.
It’s important to understand that these regions reflect where many of your ancestors were likely living in the past hundreds, or even thousands, of years. In simpler terms: your result is not a guarantee that “your great-grandfather was from this exact town,” but rather that your genetic makeup is more similar to people whose families lived long-term in these regions.
Interpreting my breakdown":
Here are my reported regions (as shown through AncestryDNA):
Southeastern England & Northwestern Europe: 42%
North East England: 15%
West Midlands: 9%
East Midlands: 3%
Central Scotland & Northern Ireland: 5%
Munster Ireland: 4%
Leinster Ireland: 2%
Northern Wales & North West England: 2%
Southern Wales: 1%
The Netherlands: 9%
Northwestern Germany: 2%
Sweden: 4%
Iceland: 2%
These results would suggest that my dominant region (42%) Southeastern England & Northwestern Europe. This means I have a strong genetic affinity to ancestors whose long-time roots were in that area. A further 15 % is North East England, and smaller percentages in the Midlands (West 9 %, East 3 %). So overall large portions of your ancestral DNA tied to different regions of England.
Then I have Gaelic-Britannic regions: Central Scotland & Northern Ireland (5 %), Munster and Leinster (total 6 %), Wales/North West England and Southern Wales (3 % together). That suggests Celtic or mixed British Isles ancestry.
Outside the British Isles, I have 9 % from The Netherlands, 2 % from NW Germany, 4 % Sweden, and 2 % Iceland. So I also have a Scandinavian/Low Countries component.
Of course, these percentages are estimates and have some margin of error. My siblings and I might show somewhat different percentages because of the randomness of inheritance. But the majority of these regions do line up with research I have already completed.
Why did my region results change over time?
Let’s be clear: my actual DNA didn’t change - just the regions themselves (and my percentages).
The reference panels and algorithms are constantly being refined. As more people test, more data accumulates, and the company can identify more fine-grained regional clusters. For example: smaller sub-regions within Sweden, or within the British Isles. This means AncestryDNA may redefine what region “West Midlands” means, or add/remove sub-regions.
Because the reference population shifts, my percentages may shift a little. And as the algorithms improve, they may adjust how they allocate your DNA segments among regions. So you might see a small portion move from one region to another, even though your heritage hasn’t changed.
This change is in how the company interprets that DNA in light of new data and improved methods. This is a good thing because it means more people are participating and refining the regional data points.
Why this matters for your family history?
The regions give clues. They can help you decide where to focus record-searching, localities to check, and family trees to explore.
The regions complement the traditional genealogical record-search (birth/death/marriage) by adding a genetic dimension.
Because your regions cover specific areas (England, Scotland, Ireland, The Netherlands, Sweden, Iceland), it makes your migratory story richer: perhaps some lines stayed in England, some moved to the British Isles, some came from Scandinavia or Low Countries.
It also reminds us to keep genealogical research flexible. The DNA might suggest regions your tree has not yet captured, and the changing regions remind you to revisit results periodically.
Some people get frustrated when their percentages change during an Ancestry update, but I’ve learned to see it as progress. Every update means the data has grown - new samples, better algorithms, clearer boundaries.
Your DNA is a constant but the understanding of it is what evolves. So if your results change next year, celebrate it! It means we’re all collectively helping the map of human history become a little more accurate.
Sources & Further Reading:
AncestryDNA® Ethnicity Estimate Explained — Ancestry Support
Understanding AncestryDNA’s Ancestral Journeys — YourDNA Guide by Diahan Southard
Making the Most of Your Ancestral Regions — Ancestry Knowledge Base
DNA Explained: Ancestry Updates Ethnicity & Renames Features (2024) — Roberta Estes
