Guest Post: What Happened at AncestryDNA This Week?

My friend and SDGS colleague, Marshall Clow, passed this to me in email this morning:

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Background: I manage five DNA tests. I will refer to them as 'ME', 'LF', 'LC', 'RA' and 'JS'. 

 * 'LF' is a parent of 'ME'. 

* 'RA' and 'JS' are parents of 'LC'. 

 I consider DNA matches which Ancestry has tagged as "Common Ancestors" as a fertile hunting ground for improving my family tree. Ancestry is not always correct in their determination, but it's always worth looking at these matches. 

 Matches that are both "Common Ancestors" and "Unviewed" are like found gold. Here are people that you've never looked at, and Ancestry wants to tell how you and they are related. A few years ago, I worked my way through all these matches for the tests I administer, seeing if I can place them on my tree. 

 Now that I've driven the count of "Unviewed Common Ancestors" to zero, I check it regularly (most days). Occasionally someone appears in this list, and I start researching them. 

 The month of August has been very slow. Usually, I see 10-12 "Unviewed" "Common Ancestors" matches each month (spread across the five tests that I manage) From 25-July until 21-August (4 weeks) there was only one. 

 On the morning of the 22nd, I checked for new "Unviewed" "Common Ancestors" matches. There were none. In the afternoon, I checked again: 

* 'ME' had two "Unviewed" "Common Ancestors" matches. 

* 'LC' had seven "Unviewed" "Common Ancestors" matches. 

* 'LF' had six "Unviewed" "Common Ancestors" matches.

* 'RA' had *twenty* "Unviewed" "Common Ancestors" matches. 

* 'JS' had no "Unviewed" "Common Ancestors" matches. 

 I looked at these matches. They were all over the map; it was not like Ancestry had made one new connection, and a lot of people were all the same set of descendants. But there's more to it than just that. 

There were new "Common Ancestor" matches that I had looked at before as well, as well as people who had been tagged with "Common Ancestors" in the past and then had that tag removed. 

 And a lot of matches that had previously had the "Common Ancestors" tag no longer did so: 

 * 'ME' had the "Common Ancestors" tag removed on 114 DNA matches. 

* 'LF' had the "Common Ancestors" tag removed on 79 DNA matches. 

* 'LC' had the "Common Ancestors" tag removed on 35 DNA matches. 

* 'RA' had the "Common Ancestors" tag removed on 114 DNA matches. 

* 'JS' had the "Common Ancestors" tag removed on no DNA matches. 

 Here's the summary of the changes in table form:

DNA Kit: ME
Previous CA Matches: 327
Added Matches: 38
Removed Matches: 114
Current CA Matches: 251

DNA Kit: LFPrevious CA Matches: 278
Added Matches: 35
Removed Matches: 79
Current CA Matches: 234

DNA Kit: LC
Previous CA Matches: 178
Added Matches: 13
Removed Matches: 35
Current CA Matches: 156

DNA Kit: RA
Previous CA Matches: 362
Added Matches: 46
Removed Matches: 114
Current CA Matches: 294

DNA Kit: JS
Previous CA Matches: 2
Added Matches: 0
Removed Matches: 0
Current CA Matches: 2

This is a big change for Ancestry. It appears to me that they have revamped their algorithm that matches up different trees, and the new matching is giving markedly different results than the old algorithm. I am also seeing a fair amount of churn in the Thrulines for the four accounts that have had all this activity, but not (in my opinion) enough Thrulines changes to account for all of the "Common Ancestor" removals. 

 For example, RA had three Thrulines changed, but none added or removed and yet he had 114 DNA matches with the "Common Ancestor" tags removed.

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Randy's comments:

After receiving Marshall's email, I checked my "Unviewed + Common Ancestor" DNA Match list, and saw 9 new ThruLines in my AncestryDNA matches. I don't have the capability, or the persistence, that Marshall has to keep track of how many matches have common ancestors and how many matches are removed from the ThruLines Match list. The last time I checked, I had about 480 Common Ancestors on my DNA Match list. I will calculate the new number soon.

I have worked through six of the new ThruLines that I have, and have added two lines from the Common Ancestor to the DNA Match to my RootsMagic family tree. I will work on the rest of the new ThruLines soon.

Here is the top of my AncestryDNA ThruLines summary. They have eliminated the "New" ThruLines number (I want it back - it was very useful!), and don't provide an "Overall" number of ThruLines (they never have - I wish they would!).



It appears to me that Ancestry.com has pruned and grown their "Big Tree" in the recent past (see my post A Reader's Take on Ancestry.com Problems - Part IV: The Ancestry Big Tree from 13 February 2019) that they use to come up with the Common Ancestors based on the family trees submitted by Ancestry.com users. Then they ran the Common Ancestors algorithm for the DNA Matches again earlier this week.

Thank you to Marshall for his work. I hope that we hear from AncestryDNA about this change sooner rather than later.

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Disclosure: I receive a complimentary all-access subscription from Ancestry.com, for which I am thankful. Ancestry.com has provided material considerations for travel expenses to meetings, and has hosted events and meals that I have attended in Salt Lake City, in past years.

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