FTDNA project administrators should be getting notices soon that announce the following changes in the threshold Family Finder customers must meet in order to be matched with each other. For those of you who like to monitor how such changes impact the number of matches you are shown, you better document your baseline data quickly. Your number of matches should change soon.
You asked for it - we listened!
For several years the genetic genealogy community has asked for adjustments to the matching thresholds in the Family Finder autosomal test. After months of research and testing, we have implemented some exciting changes effective very soon.
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.
Soon, the following changes will have been 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 has been rerun using the new matching criteria, and all new matches have been 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.
I am assuming that most of you will get additional matches -- particularly those formed by single shared segments between 9 and 19 cMs. This will not be close relatives but potentially could be with family members in the 4th to 6th cousin range. Such matches have been suppressed because the shared cMs totaled less than 20. They can be detected in comparisons run at GEDmatch on FTDNA data.
Some die hard genetic genealogists love to analyze the changes in matches reported when adjustments are made such as the one that is imminent from FTDNA. Yesterday Jason Lee reported in a ISOGG Facebook post: "Two thirds of my matches at AncestryDNA are single segment matches under 9 cM." Those wishing to dissect the differences between databases and differences in a single database before and after screening criteria is changed will have a field day as FTDNA rolls out the above change.