A long-requested change is taking place shortly at Family Tree DNA – although we don’t have a firm date as of yet. Final testing before release is still underway.
I received a notification from Family Tree DNA, as follows:
You asked for it and we listened!
Currently, the current matching thresholds – the minimum amount of shared DNA required for two people to show as a match are:
- Minimum longest block of at least 7.69 cM for 99% of testers, 5.5 cM for the other one percent
- Minimum 20 total shared centiMorgans
Some people believed those thresholds to be too restrictive, and through the years requested changes that would loosen those restrictions.
In the near future, as soon as the quality assurance process is complete, the following changes will be implemented to the matching program.
- No minimum shared centiMorgans, but if the cM total is less than 20, at least one segment must be 9 cM or longer.
- If the longest block of shared DNA is greater than 9 cM, the match will show regardless of total shared cM or the number of matching segments.
The entire existing database is being rerun using the new matching criteria, and all new matches calculated with the new thresholds.
Most people will see only minor changes in their matches, mostly in the speculative range. They may lose some matches but gain others.
This is truly exciting news, especially for people with African American heritage whose connections to matches may be several generations back in time and may not have met the previous 20cM total threshold criteria. In fact, these new thresholds may benefit many of us with deep colonial roots, but I’m hoping that people who have had few matches until now will be pleasantly surprised.
As soon as this change is released, I’ll be checking to see if I’ve gained or lost matches, and will report back as either additional information or results are forthcoming!