DNA Matches by Testing Company

Ancestry has recently announced that their DNA database now includes over 6 million individuals.  As Ancestry has the largest autosomal DNA database they are happy to announce these milestones, but accurate information on the database size of the other DNA testing companies is more difficult to obtain.

To provide some idea of how many matches you can expect if you test with the various DNA testing companies, I have compiled the data for my own DNA and my wife's DNA into a chart to show how many matches the major DNA testing companies have identified for each of us, and within that list of matches, how many matches I have been able to confirm match my paper research.

As Ancestry has the largest database, you would expect that it would generate the largest quantity of matches.  This is confirmed for both Marlene's sample and my sample.

You would also expect that Ancestry would generate the largest number of matches confirmable by paper research.  This is true for my sample, and would also be true for Marlene's sample, if she did not have a group of 5 matches on 23andMe that are all siblings / children of those siblings, which skews her data.

But the percentage of Ancestry matches that have been confirmed against paper research is certainly not as great as the percentage that have been confirmed for our samples on 23andMe and Family Tree DNA.  There are a number of reasons why this could be -

• With such a large number of matches on Ancestry, I simply have not investigated enough of them to confirm the match.
• Ancestry uses a lower threshold of the amount of shared DNA that constitutes a match, than the other testing companies do, but those more distant matches are more difficult to confirm against paper research.
• For those Ancestry users who have public family trees, I cannot view their family tree, as I do not have a paid monthly subscription to Ancestry's historical records service, making it more difficult to identify a common surname or even a region where our common ancestor may have lived.
• Ancestry does not identify which segments are shared on which chromosomes (23andMe and Family Tree DNA do), making it more difficult to see which ancestral line we may connect on.

My advise continues to be to test with as many DNA testing companies as you can afford, as they all will generate matches not found on the other testing companies' sites, but regardless, upload your DNA result to GEDmatch.com.

GEDmatch facilitates comparison of DNA samples from multiple DNA testing companies on one site, but requires those who have taken a DNA test to upload their raw DNA data file to the site (a free service).  GEDmatch limits the number of matches that are displayed to 2000, so you may not see a distant relative in your list of matches, if the amount of shared DNA puts them below number 2000 in your list of matches.

I complied the chart below to show the percentage of our GEDmatch matches that come from each DNA testing company.  More than half of our matches on GEDmatch are from Ancestry, but not the 90% that you might expect given the number of matches in each company's database.  

My best guess is that a lot of people take an Ancestry DNA test to obtain their ethnicity breakdown, but do not pursue searching for DNA relatives.

I will update these charts at some point in the future, perhaps when Ancestry hits 7 million DNA samples, but meanwhile I will continue trying to confirm the ancestral connection for our DNA matches from all testing platforms.