these slides are at

by Kitty Cooper, blogging at

When DNA Ethnicity BioAncestry Predictions are Useful and Accurate

screenshot from 23andme chromosome painting

Ethnicity (aka BioAncestry)

is the term DNA testing companies use incorrectly for 

Biological Ancestry


CANNOT be determined on a country basis for the most part


CAN be determined by Continent, usually several areas, North, South, East, West ....


usually cannot be determined on a country basis

Remember Kyle in the Ancestry DNA Ad -  who discovered he was Scottish not German?

Frankly it is hard to tell them apart as both can look Scandinavian or English...

Many Americans "know" they have

GERMAN BioAncestry

Lets look at why that might be ....

They are puzzled to see little or no German in their results

  • West German looks French
  • East German looks Eastern European
  • South German can look Italian or East European
  • North German can look Scandinavian or English

Two European BioAncestries are clear in the DNA:

Ashkenazi Jewish


But the others can overlap greatly

even more than shown in the map

for example German and English

East German Mother, Colonial Dad at MyHeritage

East German Mother, Colonial Dad at MyHeritage

compared with an actual German 2nd cousin 


Known German Ancestors at Ancestry

It turned out his parents had used a Jewish sperm donor

Stan knew he was of 100% German descent!

These were his results at Ancestry

My ancestry is well known, My father is Norwegian American and my mother was born in Munich to a Jewish father and Catholic mother

Yet each company has slightly different predictions. Even the jewish varied a bit.

Why are my results are so different at each company?






Each company has its own algorithms and reference populations. There are some public databases but many are exclusive to the company doing testing

Why are they all so different?

A reference population is a group of people living in one place whose ancestors also lived there (e.g. all 4 grandparents within 50 miles) thus representing that BioAncestry for a few hundred years

The ISOGG Wiki is my go to resource for understanding all things DNA.There is a good article about determining BioAncestry from DNA at

Why are my results different from my brother's?

Since we are not identical twins, our parents each passed along different bits of DNA to each of us, he got more Bavarian, I got more Jewish

23andMe comparison to my brother

Ancestry comparison to my brother

Siblings can get different ethnic mixes from the same parents

The ethnicity results suggest that my brother got more DNA from our Bavarian grandmother than I did

What about English, Irish, Scottish, and Welsh? Can they be told apart?

Most early American settlers on the East coast were from those ethnicities

Although there were some Germans, Dutch, French, and Scandinavians 

Dave has deep American roots as shown at Ancestry:

colonial Pennsylvania and Georgia plus Carolinas

His half brother with much Irish on his other side

Although 23andme puts all the British Isles together, it can sometimes differentiate areas, example from a man with deep Texas roots

Older British Ancestry is being studied by a project at Oxford called the people of the British Isles


The testing company has access to those results making it the only company that can show granularity by county in the British Isles

Unless your ancestors are from the British Isles

... either 23andme or Ancestry is likely to have the best bioancestry breakdown

Ancestry shows Communities: for Dave, the person with colonial Pennsylvania and Georgia plus Carolinas


Deep American roots: colonial Carolinas and Tennesee

His Communities at Ancestry


But my 4th grandmother was a Cherokee princess?

Why does that not show in my DNA?

Often these family stories are not true. Plus if it was that far back you might not have DNA from her.


However if you have someone descended on the all female line from her, then mtDNA could prove this.


If this is important to you try Roberta Estes' blog or her book


However if you have roots in the areas of the Americas that were originally Spanish, you will have Native American BioAncestry.

The Spanish soldiers who came over and stayed did not usually bring wives, so they often married native women

Tessa's father was unknown: Ancestry DNA says Hispanic New Mexico


Tessa versus her Colonial rooted mother at Ancestry

Notice the accuracy of the communities at Ancestry

Another unknown father case


23andMe has chromosome painting under Scientific Details


that function shows a picture of where each segment of bioancestry is located

Mexican Dad, American roots mom at 23andme

Puerto Rican Mom, African American Dad

Australian Mom, half Chinese Dad

clicking on an ethnicity, here Chinese, highlights those segments

23andme can give you a chromosome painting of your ethnicity as can Family Tree DNA

Ancestry can use its database of trees to give you ancestral communities

MyHeritage lets you look at your matches sorted by ethnicity

Which Company is best?

The conventional wisdom is that any ethnicity smaller than 1% is likely "noise" so not worth pursuing

I have %0.3 Finnish at 23andme but it is likely real.

Ancestry also gave me and my brother Finnish - 1%

And my Dad has even more Finnish

My brother and several cousins also have Finnish, here is one cousin's results

At 23andme you can download a CSV file of the ancestry composition of specific segments

If you have a master spreadsheet of segments, you can see who else is matching there and perhaps then you can figure out which ancestral line it is from

Or you can use the Tier 1 Matching Segment Search tool at GEDmatch to research it

Many Finnish names turn up on that segment

Luckily for me, my maternal piece at that location is not Ashkenazi but German/French

and those countries have very few testers

GEDmatch has many interesting tools including some BioAncestry calculators

called AdMix there

I have slides on how to use them here:

Jtest result for a 100% Ashkenazi Jewish person

East Med, Western Asian, and Middle Eastern all can be Ashkenazi too

BioAncestry Summary

  • 23andMe and Ancestry have the best predictions; except Briitish may be best at LivingDNA

  • German BioAncestry is not clear in the DNA

  • European Jewish and Finnish are clear; as are African, Native American, Chinese and other Asian

  • A small unusual result may or may not be accurate; check all the companies

  • It may be possible to track down the source of a segment with the tools at 23andMe plus GEDmatch

When DNA Ethnicity Predictions are Useful and Accurate

By Kitty Cooper

When DNA Ethnicity Predictions are Useful and Accurate

Ancestry Composition - Presentation by Kitty Cooper

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