Exploring the new ancestry.com DNA feature: total cMs

Ancestry.com has a new feature which shows you the total number of centimorgans (cMs) and segments for your DNA matches. You have to go and look at at specific match to find it. Once there, you click on the little “i” in a circle next to the confidence level description and a dark box will appear with the information.

Here is what that looks like for my brother and our first cousin from her account.

AncestryDNAnewCMsSmll

Ancestry has its own algorithm for removing matching DNA that it thinks is not recent. This means that these numbers will not match what you see at GEDmatch. Perhaps some of the excluded data will appear as “Ancient” over at DNA.land but not all these kits are uploaded there yet so that report will have to wait.

Here are a few examples of the numbers for my brother’s family matches at Ancestry, as compared to those same matches at GEDmatch or ftDNA:

Ancestry GEDmatch Difference
total cMs segments total cMs segments cMs
first cousin match 786.0 41 904.0 35 118.0
third cousin match 84.0 7 94.5 7 10.5
5th* 22.8 1 23.9 1 1.1
5th 1R 18.9 1 20.3 2 1.4
5th 2R* 19.2 1 29.1 2 9.9
unknown 19.5 1 31.5 1 12.0

The starred matches are kits not uploaded to GEDmatch so the comparison was with the numbers reported at Family Tree DNA. Note that I changed the default at GEDmatch to 5 cMs in order to be consistent with the threshold at Ancestry.com.

Generally, in the Ancestry algorithm, the segments seem to be reported as smaller and not all of them may be included.

For those of us that want the details of our matching DNA at Ancestry this is better than before. However we still must upload the data elsewhere in order to see the chromosome by chromosome matching details.

4 thoughts on “Exploring the new ancestry.com DNA feature: total cMs

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  1. On my Ancestry DNA match page there are no little i’s in a circle next to any match listed. Any reason for this? Thanks.

    • You have to look at the individual match. If you do not see the circled i then:

      1) you may have an old cached copy of the page; in that case hold down the control key on a PC while clicking refresh.

      2) you might not be in the USA or just not have received this feature yet. Patience is the genealogists friend.

  2. I do not have small circles with an ‘i’. I do have small circles with a ‘?’
    Clicking on this yields an explanation of possible examples for the predicted relationship.

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