Good Day- Can someone explain to me why there is a significant variation in cM match amounts from Ancestry to gedmatch, when it is the same Ancestry kit that was uploaded to gedmatch? For instance, I have a match that shows 34cM and 3 segments on Ancestry, but records as 46.3 cM on 3 segments on gedmatch. Granted it is a small match, but that is a variance of 12 cM, more than 25%. If this is how it reports, does the variance % decrease for larger matches? Thank you! Regards, Patti Easton

Patti I pretty much agree with Jim and Jon. There can be a few different reasons for a difference in cM. When Dna is tested there will often be some no-calls and minor errors, the various comparison sites use different criteria to define how many no-calls and minor errors can be included in a segment and it to still be called a match, this often affects segment length, start and stop points. At present it looks like Ancestry.com and Ftdna use fairly strict criteria with 23andme being a bit more relaxed with Gedmatch being the most relaxed. Another issues is that when Dna is tested it is broken down into tiny segments and then the raw data is reassembled by using a mapping standard called a build. The older Build is Build 36 and the newer standard is Build 37. The difference in the Builds can cause some differences in reported matches. I understand that Gedmatch and Ftdna are still using build 36 while 23andme uses build 37 at present we do not know the internal workings of the Ancestry.com software. (Using either build standard works OK but will report the match in a slightly different position and possibly a slight size difference) RPaine -----Original Message----- From: Patti Easton via Sent: Monday, December 28, 2015 6:58 AM To: genealogy-dna@rootsweb.com Subject: [DNA] Variation in cM match amounts Good Day- Can someone explain to me why there is a significant variation in cM match amounts from Ancestry to gedmatch, when it is the same Ancestry kit that was uploaded to gedmatch? For instance, I have a match that shows 34cM and 3 segments on Ancestry, but records as 46.3 cM on 3 segments on gedmatch. Granted it is a small match, but that is a variance of 12 cM, more than 25%. If this is how it reports, does the variance % decrease for larger matches? Thank you! Regards, Patti Easton ------------------------------- To unsubscribe from the list, please send an email to GENEALOGY-DNA-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message