False Positive Distant Matches - Saving 6-8cM Matches

 While we are all frantically attempting to capture our Distant DNA Matches (6-8cM) on Ancestry DNA (more on how to do this below), I came across an interesting piece of information which I thought I would share.  

Someone in the Facebook Group where the script created by Roger Froysaa is being shared and discussed asked a question regarding distant matches and false positives.  If DNA doesn't lie, then how could there be false positives?

Someone answered this with an interesting article.  It seems like the algorithms used by the companies who host the DNA test kits do not separate maternal and paternal DNA.  There could be a match for a segment of DNA that appears "half-identical" between you and one of your matches, but these genomes were essentially smashed together when the algorithm didn't separate Mat/Pat DNA.  The segment of DNA was essentially zipped together by zig zagging from the maternal and paternal DNA which when the alleles were put together, happened to arrange in a way that resulted in a match to someone who either had the same thing happen, or actually has this segment of DNA.  This is a pseudosegment / spurious segment / erroneous segment / phantom segment.

In a nutshell - a false positive match could be the result of an error in the algorithm used by the test company, or because of the match using alleles from opposing chromosomes.

I am by no means a DNA expert, so feel free to correct any misinformation.  I just thought I would share this interesting bit of information I came across.  

Need help saving your 6-8cM matches?? I used the script Roger Froysaa made and shared into an Ancestry DNA group on Facebook.  This allowed me to run the script and instead of saving matches one by one into a designated group, it did it on its own while I left my computer for a few hours.  Ancestry DNA is removing Distant Matches from everyone's DNA Matches at the end of August, so the deadline is quickly approaching!  If any of these 6-8cM matches are tagged or saved into one of your Groups on Ancestry DNA Matches then you are essentially saving or preserving them beyond this mass deletion and you will be able to access this information in the future.  You can title the group whatever you want.  I ran the script first for 7-7cM then 6-6cM then 8-8cM.  I just figured 7 would be the best to start for whatever reason, it has a larger # and more likely to be actual matches than 6cM.  If you would like to join the group, I can provide you the information, and help out with the script if you have a Mac!