Helpful Trick for Shared cM on AncestryDNA

During a genealogy research trip to Salt Lake City, it became clear that a helpful trick related to shared cM on AncestryDNA that I regularly use was not known by many of my USA colleagues.  It is not needed so much in the USA as they have many more DNA matches than we have in the UK.  As lots of people do not know how to use it, I want to share it with the wider world.

AncestryDNA provides a Shared Match list for each of your DNA matches. These are given if you share more than 20cM with the shared match and your DNA match also shares more than 20cM with your match. This means that even a useful match (at say 18cM) would not appear in your shared match list. When you have thousands of matches greater than 20cM (this is the cut off for 4th cousins or closer), you will always have several, if not many, shared matches to help identify which family line the match is on. In the UK where we have a lot fewer matches, we often have no shared matches at all with a match, or the level of shared DNA is much lower such that it is below the 20cM limit.

If you either manage or can view more than one DNA kit on Ancestry, there is a trick to spot shared matches with those kits below 20cM. If you find a DNA match that does include another kit in your family on the Shared Match list, click on the user name of the match (or the manager of the match).

On the user ID page, there is an option to choose any of the DNA kits you manage. This allows you to see if they match that kit at any level (e.g. above 6cM).

In this case, the managed kit matches at 19.9cM across 2 segments so only just outside the cutoff of 20cM. This helps to indicate that the match is on this line of the family.

Several of my USA friends have been pleased to have this trick explained – hope it helps you too!

The content of this blog was originally published on 22 January 2019 on my previous blog. Some of the text has been adapted. The screenshots were taken prior to the Ancestry Profile page updates which took effect at the end of February 2019.

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