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Geneanet DNA matches update

Posted by Jean-Yves on Apr 12, 2021

After the release of the Chromosome Browser, some of you pointed out the fact that many DNA matches were composed of segments located at the same positions on the chromosomes. Here we address those concerns and present the changes we did to offer you better results.

In this previous note, we explained that some DNA segments are shared by a large number of individuals, thus generating many DNA matches that are not very relevant from a genealogical point of view. Thanks to the files uploaded to Geneanet DNA, we have been able to identify a certain number of regions from which these segments originate and take them into account in the calculation of the DNA matches levels of accuracy. Actually, when all the shared DNA segments are only present in the identified regions, a DNA match has a low accuracy (red dot), so it is normal to see a redundancy of some segments within your DNA matches.

In order to provide more relevant results, we have changed the criteria for displaying a DNA match. Resulting in changes in your list of DNA matches in the next days. Here are the changes included in this update:

  • DNA matches consisting only of segments present in the identified regions (currently in low accuracy) will no longer be displayed;
  • DNA matches consisting of some segments present in the identified regions will still be displayed, but these segments will be identified in the Chromosome Browser and in the exported CSV file;
  • DNA matches composed of small segments (less than 12.5 cM) will now be displayed.

Following these changes, the levels of accuracy are also evolving:

  • The low accuracy level (red dot) now corresponds to DNA matches composed of segments whose size does not exceed 10 cM;
  • The medium accuracy level (orange dot) now includes DNA matches composed of segments larger than 10 cM (but not meeting the high accuracy thresholds) as well as DNA matches with at least half of their segments present in the identified regions (even if these matches pass the high accuracy thresholds).

As a result of this update, the number of your DNA matches may decrease or increase, but no matter their quantity, the purpose of these changes is to increase their quality.

However, keep in mind that whatever the color of the dot, the detected relationship may be real, or on the contrary inexistent (especially for shared DNA percentages lower than 0.7%). The three levels of accuracy that we propose are simply intended to allow you to focus your research on the relatives that we consider the most relevant from a genealogical point of view.

These improvements will soon allow us to provide you access to a list of DNA matches shared between you and your genetic relatives.

See you soon and enjoy your discoveries on Geneanet!

Your DNA matches

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Thank you for the update.

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