DNA Testing: A Case Study With Staggering Conclusions

Read this DNA testing case study before throwing your money at the genealogy DNA testing companies. Maybe you’ve read some reviews or seen a list of “the top DNA tests,” but have you ever seen actual results? This article takes you through an actual DNA testing case study. It compares the detailed results from the six major DNA testing companies, pointing out the strengths and weaknesses of each. The study concludes with solid recommendations – no hemming, hawing, or hedging. Following the recommendations will save you money.

This report compares the quantity of DNA matches from six different companies at six unique matching thresholds. It also lists the major genealogical features and tools available at each company, along with standard pricing.  The case study compares the results of the six major genealogical DNA testing and matching sites: Ancestry, FamilyTreeDNA, MyHeritage, 23andMe, LivingDNA with FindMyPast, and GEDmatch.

This is Part 1 of a 2-part case study. Part 2, DNA Ancestry Heritage Tests Are A Complete Farce covers the heritage testing and reporting.

DNA and CentiMorgans

Genetic DNA testing has a unique and often confusing vocabulary.  However, we will quickly cover the basics.  The first thing you need to know is that there are three types of genealogical DNA and three types of testing:

1. Y-Chromosome DNA is passed from father to son
2. mitochondrial DNA (mtDNA) is passed from the mother to each child
3. autosomal DNA is comprised of the 22 chromosome pairs that are a mixture from your parents

There are unique tests and reports for each.  This case study covers autosomal DNA testing, the most popular form of DNA testing.

The second thing you need to know is that the amount of DNA two people share is expressed in centiMorgans (cM). Humans have about 7,000 cM of autosomal DNA. We get one-half of our DNA from each of our parents, which means we share about 3,500 cM with each parent.  The quantity falls off quickly as we move out further on our trees.  The averages and ranges for various relationships are:

• 1st cousins: 866 cM (396 – 1397)
• 2nd cousins: 229 cM (41 – 592)
• 3rd cousins: 73 cM (0 – 234)
• 4th cousins: 35 cM (0 – 139)
• 5th cousins: 25 cM (0 – 117)
• 6th cousins: 18 cM (0 – 71)

The third thing you need to understand is that with the exception of your parents and children, the amount of DNA you share with other relatives can vary widely.  For example, we share 73cM of DNA with our third cousins on average, but the amount can range from zero to 234.  You can learn more about centiMorgans and relationship ranges on our Genetic Genealogy page.

DNA Testing Case Study Results

Now that you have a basic understanding of the terminology, let’s compare the results from six DNA testing companies.  The DNA used in this DNA case study is my own, and the report reflects actual results.

The table below is broken into three sections: DNA match quantities, tools, and pricing.  The DNA Matches section shows the quantity of matches above various thresholds.  The first tier is above 100cM, the second tier is above 75cM, etc.  Many experts believe that values below 20cM are unreliable, and I, therefore, have a separate tier for that group. Please note that 23andMe cuts off its matching reports at 25cM.

Ancestry is the largest testing company and has the largest database, which is a key factor in finding DNA matches.  My AncestryDNA test has identified 89,258 DNA matches for me – 10x more than any other testing company, but about 97% of those matches (86,548) are below 20cM, a level that some might consider unreliable.  However, using the other tools at Ancestry, I have discovered valid relatives and new ancestors from many of these matches.  Ancestry easily has the most matches in the > 100cM tier, which are the highest quality matches.

FamilyTreeDNA produced the largest quantity of matches in three different tiers: > 50cM, > 25cM, and > 20cM.  It appears their cutoff for reporting is 20cM, although I cannot explain why there are 14 reported matches below that level.

MyHeritage has a decent quantity of matches, and it has the best lineup of tools in my opinion (more on that later).

23andMe had disappointing matching results, and the company appears to be completely lacking in relationship-finding tools.  This is the only site that does not support a family tree, which is probably the most basic of all genealogical tools.  23andMe might compare better if we were looking at health-related genetics, but as a relationship finding, family tree building resource, it has very little to offer.

LivingDNA and FindMyPast have teamed up with the former to perform the DNA testing and analysis, while the latter is providing the tools for genealogical research.  Please note that these are UK-based firms, and therefore the DNA database currently consists mostly of UK residents.  I (the test taker in this case study) am a multi-generational North American descendant, and so my quantity of matches is expected to be lower. A UK resident will likely see different results.

GEDmatch is not a testing company, although you can upload any other test to the website for further analysis free of charge. This was one of the original DNA analysis companies, and its database is used by many academic researchers. It has a rich set of tools.

Shared Matches:  All these companies have the ability to identify DNA matches that are common to both you and another tester.

Upload Other Test: Ancestry and 23andMe are the only two companies that require you to buy the DNA test from them.  All the others allow you to upload another company’s DNA test.

Clustering and Auto-Triangulation: Clustering is the process of segmenting your matches into groups that are common with each other.  The most basic example is two clusters – those from your father’s side of the family and those from your mother’s side.  In practice, it is beneficial to expand this out to 8 or 16 clusters (great grandparents or great-great-grandparents).  Triangulation is the process of identifying the common ancestor between three DNA samples.  MyHeritage excels in this area, and Ancestry provides some group identification tools that can help facilitate manual clustering efforts.

Upload a Tree: The ability to upload a tree is key.  You do not want to develop and maintain a tree at each site.  It is much easier to keep your main research at one site, then download your tree from there and upload it to other sites.  All but 23andMe provide this function (another strike against 23andMe).

Common Ancestor in Tree: Ancestry says I have 89,258 DNA matches.  Where do I begin? Fortunately, Ancestry and MyHeritage show which of my DNA matches also have a tree containing an ancestor that is common to my tree.  Instead of scratching my head as to where this distant cousin might fit in my tree, I now have a clear road map.

Other Tools:  All these sites have many additional tools, too numerous to list and comment on.  Many have chromosome browsers, which I consider a more advanced tool. I have identified the tools I believe are most important in deciding which DNA test to purchase.

Pricing:  These are the prices for DNA collection, testing, and basic reporting.  There may be extra charges for additional site functions and access to tools. All companies have a list price and offer various promotions throughout the year.  With a little patience, you can save some money and not have to pay the full list price.

DNA Testing Case Study Conclusion and Recommendations

For anyone wanting to take a genealogical DNA test to help determine ancestral relationships, I recommend the following:

1. Buy Ancestry’s DNA test when on sale. Try for a price of $79 or better.
2. Download Ancestry’s raw DNA test files, and then upload those files to FamilyTreeDNA, MyHeritage, LivingDNA, and GEDmatch. You will now have your DNA test results at five different sites for the price of one.
3. Build your family tree at WikiTree. It is a completely free site, while some of the DNA testing companies might charge for this.
4. Download the GEDcom file (a standard file format for moving trees between websites and applications) of your tree from WikiTree, and then upload your GEDcom tree to Ancestry, FamilyTreeDNA, MyHeritage, FindMyPast, LivingDNA, and GEDmatch. You will now have your family tree at seven different sites for free.
5. Use and play with all the free features at these sites before spending any additional money.

Part 2 of this case study, DNA Ancestry Heritage Tests Are A Complete Farce, is required reading if your objective is to learn about your ancestral heritage and ethnicity estimates.

Further Reading

Genetic Genealogy – an introduction to DNA, DNA testing, and the randomness of generational DNA transmission.

Genealogy Websites – a summary of the companies and websites discussed in this article.

Home Page – Rowland Genealogy is much more than just a tree, and it is for much more than just Rowland families. Take a look.

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