18 September 2013

Why So Much Excitement about Ethnicity Predictions?

AncestryDNA made a recent announcement about updates to the ethnicity predictions available with their autosomal DNA (atDNA) test. The first sentence on their web page for ordering a DNA test is:
Discover if you're part Scandinavian, West African, or maybe Native American.1
The first sentence describing a Family Finder atDNA test at Family Tree DNA is:
NEW! Discover close relatives and your ethnic percentages with Family Finder!2
At 23andMe you have to click on the Ancestry link at the top of the home page before you scroll down and see:
Find out what percent of your DNA comes from populations around the world, ranging from East Asia, Sub-Saharan Africa, Europe, and more. Break European ancestry down into distinct regions ...3

I caution people about putting too much faith in these ethnicity and regional predictions for two reasons that still apply even if new advances in our knowledge have been made recently.
  1. Because of DNA recombination you may not have detectable amounts of DNA representing all of the ethnicities or geographies you see in your full pedigree chart.

    Blaine Bettinger described this well in a post several years ago titled, "Q&A: Everyone Has Two Family Trees – A Genealogical Tree and a Genetic Tree."4 While Blaine was answering a question about why a known cousin was not listed on a person's DNA match list, the answer is just as applicable to the question of why a person's predicted ethnicity percentages isn't reflected in the known pedigree of that person. Each of us inherits only one-half of the DNA of each parent. This also means about one-half of each parent's DNA is lost in each generation except where some bits are inherited by one offspring and not others. As we go back more generations we have inherited less DNA from those ancestors.
  2. The world population is about seven billion today.5 At most, a few hundred thousand people have taken genealogical DNA tests.6 This means that fewer than one/ten-thousandth of the world has been tested. That is a very small sample size.

    As more people test we will learn more about accurate interpretation of the DNA data. We are still in the infancy of this new science. I highly encourage researchers to test so we can learn more faster. You will learn some interesting information about your DNA. But I caution against making life-altering decisions based on today's technology and knowledge level, even with the recent updates.

For an interesting map showing how the boundaries of Europe have changed over the years take a look at this map (thanks to Debbie Kennett for sending the link to several DNA mail lists):


Now think about how those changes make it difficult to relate a segment of DNA to a particular country. I have to admit that I was surprised at the constantly changing European landscape even though I have always been interested in and constantly read about history. Anyone who does not understand human migrations, how those migrations don't really coincide with political boundaries, and how our DNA makeup is not a reflection of our entire pedigree due to random recombination, could have a difficult time understanding their ethnicity predictions based on DNA.

For more information on ethnicity predictions also known as Bio-Geographical Analysis (BGA) see:

Dr. Doug McDonald (the developer of one of the early programs for Bio-Geographical Analysis), "Doug McDonald on Biogeograpical Analysis," 9 September 2012 guest post, DNAeXplained – Genetic Genealogy blog of Roberta Estes (http://dna-explained.com/2012/09/09/doug-mcdonald-on-biogeograpical-analysis/).

For more information on the updated AncestryDNA ethnicity predictions see these articles and the links within them to other articles:

Blaine Bettinger, PhD, JD, "AncestryDNA Launches New Ethnicity Estimate," 12 September 2013, The Genetic Genealogist (http://www.thegeneticgenealogist.com/2013/09/12/ancestrydna-launches-new-ethnicity-estimate/).

Debbie Kennett, "My updated ethnicity results from AncestryDNA - a British perspective," 17 September 2013, Cruwys news (http://cruwys.blogspot.com/2013/09/my-updated-ethnicity-results-from.html).

Judy G. Russell, JD, CG, "DNA disappointment," 15 September 2013, The Legal Genealogist, (http://www.legalgenealogist.com/blog/2013/09/15/dna-disappointment/).

Randy Seaver, "First Look at my AncestryDNA Ethnicity Update - Post 2: More DNA Results," 13 September 2013, Genea-Musings, (http://www.geneamusings.com/2013/09/first-look-at-my-ancestrydna-ethnicity_13.html).

All URLs accessed 18 September 2013.

1. "One simple DNA test. A world of discoveries," AncestryDNA (http://ancestrydna.com/).

2. "Family Finder," Family Tree DNA (http://www.familytreedna.com/family-finder-compare.aspx).

3. "Your story begins as far back as you can imagine," Ancestry page, 23andMe (https://www.23andme.com/ancestry/).

4. Blaine Bettinger, PhD, JD, "Q&A: Everyone Has Two Family Trees – A Genealogical Tree and a Genetic Tree," 10 October 2009, The Genetic Genealogist (http://www.thegeneticgenealogist.com/2009/11/10/qa-everyone-has-two-family-trees-a-genealogical-tree-and-a-genetic-tree/).

5. Haya El Nasser, "World population hits 7 billion," 31 October 2011, USA TODAY (http://usatoday30.usatoday.com/news/world/story/2011-10-30/world-population-hits-seven-billion/51007670/1).

6. "Autosomal DNA testing comparison chart," ISOGG Wiki, International Society of Genetic Genealogists (http://www.isogg.org/wiki/Autosomal_DNA_testing_comparison_chart); gives an estimate as of August 2013 of 640,000 people in the autosomal databases of 23andMe, Family Tree DNA, AncestryDNA, and National Geographic Genographic Project Geno 2.0.

7. pierre_mesyne, "abkebab's Map of Europe 1000 AD to present with timeline," LiveLeak (http://www.liveleak.com/view?i=14d_1348362692).

To cite this blog post:
Debbie Parker Wayne, "Why So Much Excitement about Ethnicity Predictions?," Deb's Delvings Blog, posted 18 September 2013 (http://debsdelvings.blogspot.com/ : accessed [date]).

© 2013, Debbie Parker Wayne, CG, CGL, All Rights Reserved


  1. Debbie - this and your previous post about ethnicity predictions are great! I'm not a fan of so-called "Genetic Exceptionalism," so treating DNA like any other record is perfect!!

    This post also motivated me to update my original "Two Family Trees" post with images that I include in my presentations to help explain the concept.

    1. Fantastic, Blaine. I can't wait to see your updates. Two different "trees" does seem to be a difficult concept for some to grasp. Your explanation is easy to understand and so pertinent to this conversation.