Act Quick! Ancestry to Update AncestryDNA Match Formula, Matches Under 8 centiMorgans will be Lost

Have you tested your or a family member's DNA at AncestryDNA?

The news on the web in the last day or so is that Ancestry now has 18 Million tests sold. But more importantly Ancestry is in the process of updating its matching formula and very soon AncestryDNA tests are going to lose some matches -- specifically those 8 centiMorgans and below. (Currently the minimum match is 6 cMs.) It is not clear if 8 cM is the new minimum or if tests will lose those matches at 8 cM too.

Unlike the last change in the algorithm matching formula, this time AncestryDNA test owners/administrators are not getting the opportunity/option to download a test's matches as a CSV file before the change. (Very disappointing Ancestry!) Note: this update will not change ethnicity estimates.

So, because Ancestry recently sent "Cease and Desist" letters to various third-party DNA services and their very helpful analysis tools are no longer available to those with AncestryDNA tests, what can we do? (We talked about these third-party DNA services at our last in-person Let' Talk...Genealogy meeting in March.)

According to various bloggers and other sources, those with AncestryDNA tests will have manually review each test's matches and make sure they have done at least one of three things in order for a low centiMorgan match to NOT disappear after that change in matching formula.

1. Add a match to a user-defined group (one of those 24-color circles).
Hopefully you have been using these color-coded groups to create surname groups to help sort your matches. Don't want to mess up your surname groups? Do you have an undefined color group available? If yes, create a new group and call it something like 2ReviewMatch. The number will put the group at the top of this list and make for less scrolling if you have a lot of groups set up.

2. Enter something in the note field.
Hopefully you have been using the notes field to keep track of who the match is and how you are related along with the Most Recent Common Ancestors your and the match share.

3. You have sent a message to the match (other member).
We do not suggest you flood every one of your matches with a  message.

If you have stuck some matches in the trash, decide if you need to rescue any from the trash and do one of the three things listed above in order to cause Ancestry to keep the low centiMorgan match.

In addition, this change in the matching formula will likely effect Thru-Lines matches. Some Thru-Lines and DNA matches could disappear. So review each of your tests' Thru-Lines and take screen captures to record your current Thru-Line matches just in case they change. And for any Thru-Line DNA Match make sure you have done at least one of the three things -- add a note, assign a group, send a message -- so you don't lose that DNA match after the match formula change. You might lose the Thru-Line but doing one of the three options should keep the match in your DNA Match list.

[Note: If you need to know how to make a screen capture, check out the Tech Tip video on our YouTube Channel.]

Ancestry is doing this (updating its formula) to remove false matches/matches by chance. But the reality is that some valid matches might get lost when the pool water is tossed out. One change that will come with the AncestryDNA update is the addition of information on the largest segment size shared with a match. But we suspect that we should not hold our breath for Ancestry to give AncestryDNA users a much desired chromosome browser like what is available at every other single DNA/Genealogy testing company.

Now you are probably asking how do I decide which of these small centiMorgan matches might be helpful to keep. There are several ways.

Start by looking at the Shared Matches of your Known Matches (those matches that you know who and how you are related) and making sure these shared matches all have a note or one of the color-coded groups assigned to each match. 

Doing this will catch those shared DNA matches with and without trees.

Applying a color-coded group is probably the quickest way of the three possible methods to keep a low centiMorgan match.

If you have a lot of surname groups but do have a few unassigned color groups, create (on each DNA test administrated) a group called 2ReviewMatch and assign any match desired to be kept to this group. Adding a separate group, ensures your surname groups are kept to just those that have been confirmed as being from that surname. And it gives a quick way to keep these smaller matches that might be of value.

Next look click on the Common Ancestors filter and look through all those DNA matches and the Shared Matches of each of those DNA Matches with whom you share a Common Ancestor. Add a note or assign a group to any match you want to keep. This will catch those DNA matches with trees.

Search each test's match list for the each family surname in that test's pedigree. Add a note or assign a group to any low centiMorgan matches you want to keep. This will catch those DNA matches with trees.

Search each test's match list for the locations where you know your ancestors settled. While you could include a surname in this search doing the search without a surname will catch more matches. It is likely someone in the family was born there. And again add a note or assign a group to any low centiMorgan matches you want to keep. This will catch those DNA matches with trees.

As an example, if your ancestors came to Macomb County do a birth location search for "Macomb County, Michigan, USA" with no surname to catch any DNA match with someone born in Macomb County in their tree. Add a note or assign a group to each match so the match will survive the match formula change. You could also search by city or township but searching by county should catch any location in the county. Repeat for any location your ancestors lived or had children born.

You can also search by username either for a specific person or for any username containing a surname you are researching.

You can also search by Shared DNA filter looking at all matches from 6 cM to 8 cM and scroll thru the resulting list looking at the usernames. Realize that you may have thousands upon thousands of DNA matches in the range of 6 cM to 8 cM. Many are likely matches by chance rather than matches by descent.

The point at the moment is to make sure you complete reviewing each of your DNA tests for any low centiMorgan matches that might be of value to you before Ancestry implements the new matching formula. Word on the web is that this change over will happen in August. But since an exact date is unknown assume you have to act as quickly as possible.

A banner on the AncestryDNA page went up last night announcing the impending change.

For an estimate of the time involved, it took about three hours to do a review of the matches of this author's own test. It took about two hours each to review the administrated tests of a parent and two uncles (one from each side). To review each full-sibling's test will likely take just as long for each as reviewing one's own test.

Good luck everyone. Hopefully you discover something new while doing this review.

See you soon at Mt. Clemens Public Library! 
(Some day in the future. Please be patient.)
LE