What do AncestryDNA's new ethnicity results mean?

By Rosemary Collins, 26 September 2018 - 11:38am

We talked to the DNA testing company about their new method for analysing customers' ethnicity

AncestryDNA ethnicity estimates
AncestryDNA has increased the number of regions in its ethnicity estimates

If you've taken an AncestryDNA test, you might have noticed recent changes to the ethnicity estimates of your family history on the website.

This is because from 12 September, AncestryDNA began offering customers the chance to view an improved method of analysing their genetic heritage.

Its algorithm can now more precisely estimate both the regions the customer's DNA comes from and the percentage assigned to each one.

Ancestry develops the estimates by comparing the customer's DNA to a reference panel of DNA from people with known origins.

The new reference panel contains 16,638 samples representing 43 overlapping global regions, compared to the previous panel of 3,000 samples from 26 regions.

For example, Scandinavian DNA is now separated into Norway and Sweden and there are nine new regions in Asia.

The new process also analyses groups of DNA markers at once, instead of single markers.

"It better mimics how DNA is passed down in real life," Dr Barry Starr, director of scientific communication at Ancestry, told Who Do You Think You Are? Magazine.

Some AncestryDNA users have complained on social media that the update has led to large ethnicities in their results disappearing, or new ethnicities appearing.

However, Dr Starr said that the new results had a "higher precision" than before.

For example, a single marker in British DNA that resembled Iberian DNA markers had led to British customers being assigned Iberian heritage. However, the Iberian region has been eliminated in the updated version.

Dr Starr advised users who were unsure of the accuracy of their new results to look at the size of the percentage range given before deciding "whether you should accept the ethnicity".

AncestryDNA stated that the updated process correctly assigned an average of 78.9% of genetic ethnicity for single-origin individuals in the reference panel.

There is also debate about how useful ethnicity estimates are for family historians. The estimates will trace your genetic heritage to 500-1000 years ago, before most people are able to identify their family line.

Writing for Who Do You Think You Are? Magazine in May 2017, genetic genealogist Debbie Kennett described this type of analysis as "still in its infancy".

She warned: "Do not expect the percentages to correspond with your genealogical ancestry… If you test with a number of companies you will find that you get markedly different results."

However, Dr Starr said: "Often because there wasn't much movement back then it's still useful for comparing modern relatives."

He pointed out that the ethnicity estimates were "lining up really well" with AncestryDNA's Genetic Communities feature, which identifies more recent ancestors. This, he said, gave the scientists confidence in the accuracy of their results.
 

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