I've always cast my 'DNA Net' wide because I am trying to find matches to distant cousins, but a few weeks ago something happened that I have not noticed before.
My other siblings have tested and it is not unusual to find a match that only matches one of us. I've come to expect that. But last week a match from Company A DID NOT MATCH ME AT ALL ON COMPANY B'S SITE. That has NEVER happened to me. So, I compared several of the matches and this is what I found.
PR shares 29.2 cMs on one segment with ME at company A. They are not a match at company B.
CB shares 27.6 cMs on one segment at company A and only 21.93 at company B.
CP shares 47.1 cMs on one segment at company A and only 22.55 at company B.
SB shares 37.16 cMs on one segment at company A and only 16.99 at company B.
The match difference to CB was not enough to alarm me, but I wanted to know why PR was not a match at all at company B and the others were roughly half. These are all matches on the same chromosome and are the only segments the testers match on. They are also all well proven cousins to a single family. All the locations reported overlapped with each other.
The difference between the match analysis was with the SNPs reported. Company B reported on roughly half of the number of SNPS that company A reported. The first match or PR, was the lowest number of SNPS reported at company A, so I can only speculate that the total number was below a reporting threshold at company B.
This experience reminded me of two things - SNPs matter and if cMs shared do not seem 'right', check with another company.
If I was only working with Company B, I would not have found this important distant cousin! PR's match placed a previously known, but unconnected group onto my tree and helped me find three other distant cousins!
Cast your DNA net wide!