DNA Match Changes at Ancestry.com

As is the case with everyone who has had a DNA test at Ancestry, my small matches are gone.  (However, I did go through the match list of my parents and my sibling and 1st cousins, “saving” small matches that were of interest (like “Thru Lines” matches) by marking them with a group identifier or making notes.

For me, the issue was removing old notes for small matches where I had indicated “doesn’t match mom or dad” so those false matches would not be saved!

The blessing of having both your parents alive and willing to test means you can check any of your own matches to validate whether they match one of your parents (if your parents give you collaborator access).  I had already determined — via 3rd party tools — that over 25% of my matches were invalid.  Meaning they didn’t match one of my parents.

So, all in all, I’m not at all upset at losing matches.  Especially if it speeds up server response time.

How many matches did my family members and I lose?  Over 50% in each case!

Ancestry Match Counts 912020

The reduction in matches (everyone with < 8 cM of DNA shared) isn’t the only change. Ancestry also updated the number of shared segments with your matches. Mom and Dad still show more than the 22 autosomal segments they share in actuality, but it’s a lot closer. You can see that all he segment numbers go down for my matches with my closest kin.

My segments with my father were always fewer than with my mother. One reason is that there are fewer recombinations passed down from males, as I understand it. Another reason may be that my dad and I tested back in 2012, and therefore tested under a different version than my mother, who tested years later.

Here’s a list of my mom’s top matches, noting old number of segments compared to new number of segments. Segment number only changed when appropriate, so some of these 50 cM matches show no change.

Mom_AncestryMatches_Segs_LargeSeg

The last change at Ancestry DNA was the addition of longest segment information.  From what I’m hearing, this feature will be most useful to those who have significant endogamy in their ancestry (Acadian French, Ashkenazi Jewish, etc.)  However, it can be useful if your match has tested elsewhere, and you have the chromosome segment information.   

For the match below who has tested elsewhere, I already know that my mother’s (and mine, for that matter) primary segment match is on chr 9, and is hugely long (60 – 90 cM) per other vendors.  So, seeing the below information validates that Ancestry shows the match on chromosome 9 as well, despite the fact they don’t tell you where you match.  

The longest segment is calculated before Ancestry’s algorithms massage the data by removing “pile-up” regions (shared by many people) which are not considered genealogically relevant.

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