I only counted segments 5 cMs and over when comparing.
Starting the comparison with a double 5th cousin who has tested with all 3 companies:
This cousin has results at the 3 major companies plus GEDmatch. In this case AncestryDNA seems to have removed the 9 cM segment on Chromosome 6. This same segment was removed from two other relatives of this match, also. From totals around 24 cMs with GEDmatch and the other two companies we go down to a total of 13.404 at AncestryDNA.
|AncestryDNA total shared 13.399 cM Total|
|Family Tree DNA 23.41 cM Total|
|GEDmatch cM Total 25.2|
|23andMe cM Total 24.3|
Moving on to this match who has tested with the 3 major companies:
In this case AncestryDNA cut the cM total from 25 to 26 cM's to 6.748. This would mean, if Ancestry is right, this may not be a true cousin match. I haven't established a relationship in this, case so far. So they may be right in this case?
|AncestryDNA Total 6.748|
|Family Tree DNA Total 25.27|
|23andMe Total 26.2|
The particular match is a known, confirmed, 4th cousin. AncestryDNA predicts he is a 5th to 8th cousin. AncestryDNA totals are much smaller with only 6.748 total, while 23andMe says we share 32 cMs. I tend to believe the higher number.
|AncestryDNA 4th cousin match total 6.748 cMs|
|23andMe 4th cousin match total 32 cM's|