April 26, 2017

Thumbs-Up: AncestryDNA Improves Genetic Matching Technology

ancestrydna matches improvedDouble good news: AncestryDNA has made some improvements to the way they calculate your genetic matches, but they haven’t messed with the site format or layout. There is one downside–so keep reading.

Change is afoot at AncestryDNA. Again.

While stability and predictability seem like honorable qualities in a company or product, when it comes to tech tools, in the ears of tech companies, those words sound more like dated and old. Of course, we are used to this by now. I had a client tell me recently that he wanted to be in touch sooner, but his grandson “upgraded” his computer to Windows 10 and then promptly left for college the next day, leaving him fighting with a new interface and operating system.

The good news is, you won’t have this problem with Ancestry’s new update. There aren’t any changes to the interface or the layout of the information. In fact, many of you will not even notice at first that your match list has changed. You’ll just see this notification when you log in:

AncestryDNA match improvement announcement

But in fact, there likely have been some adjustments made to your match results:

  • Some of your third cousins have been demoted to fourth cousins.
  • Some of your fourth cousins have been demoted to 5th-8th cousins.
  • Some of your Distant Cousins have disappeared off your match list
  • You have new cousins on your Distant Cousin match list.

In general, from what Ancestry has showed us, you gain more than you lose.

Changes in the dregs of your match list may not seem like that big of a deal. But Ancestry has made some big changes in the way that they are calculating matches. They are getting better at it. Which means you match list is now more representative of your ancestral connections, even at the very distant level.

There are two big pieces to this matching puzzle that Ancestry has tinkered with in this latest update: phasing and matching.

You will remember our discussion on DNA phasing and how it can impact your matching. Ancestry has developed a robust reference database of phased DNA in order to better phase our samples. Basically, they have looked through their database at parent-child duos and trios and noted that certain strings of DNA values often travel together. It’s like they have noticed that our DNA says “A black cat scared the mouse” instead of  “The brown cat ate the mouse” and they can then recognize that phrase in our DNA, which in turn helps our DNA tell the true story of our heritage.

In addition to updating the phasing, Ancestry has revamped their matching method. In the past they viewed our DNA in small windows of information, and then stitched those windows together to try to get a better picture of what our DNA looked like. Now instead they have turned to a point-by-point analysis of our DNA. Again to use a sentence example, with the window analysis we may have the following sentence windows:

ack and J

ill went t

he hill t

etch a pai

l of water.

AncestryDNA match comparisonOf those windows, you may share the “etch a pai” with another individual in the database, earning that cousin a spot on your match page. However, the truth is, that bit could say “sketch a painting” or “stretch a painful leg” or “fetch a pail.” With Ancestry’s new method, they are able to see farther on either side of the matching segment, making this clearly “fetch a pail.” That means better matching, which means more confidence in your cousin matches.

The downside to this update is going to come in the reorganization of some of your relationships. Ancestry has tightened their genetic definition of your third and fourth cousins. Basically, that means that some of your true 3rd cousins are going to show up as 4th cousins, and some of your true 4th cousins are going to be shifted down into the abyss of 5th-8th cousins.

This brings us to the downside of this AncestryDNA update: changes to the Shared Matches tool. The shared matches tool allows you to gather matches in the database that are related to you and one other person, provided you are all related at the 4th cousin level or higher. This tightening of the belt on 4th cousins means that some of them are going to drop through the cracks of that tool, really limiting its ability. Grr. Hopefully Ancestry will fix that, and expand this tool to include all of your matches. They have their fairly good reasons for this, but still….

So, as the winds of change blow yet another iteration of the AncestryDNA match page, I think we can see this as an overall win for doing genealogy with our genetics at Ancestry.

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About Diahan Southard

Diahan Southard is Your DNA Guide here at Genealogy Gems! She has worked with the Sorenson Molecular Genealogy Foundation, and has been in the genetic genealogy industry since it has been an industry. She holds a degree in Microbiology and her creative side helps her break the science up into delicious bite-sized pieces for you. She's the author of our DNA guides Getting Started: Genetics for Genealogists, and Y Chromosome DNA for Genealogists (click STORE in the menu above)