Margaret and others I would be interested in your opinion on the following. A couple of days ago I watched a YouTube video suggesting that even if you have one or more very good segments of DNA matching with someone and some smaller ones under 7 centiMorgans, that you should actually ignore those small segments as they are probably still background noise, Even though you have one or more other good segments.
I had never considered it before, but it now seems a logical argument.
Martin
Martin, For those of us who tested at Ancestry we get many thousands of '5th to 8th cousins', ranging down from 19.99 cMs to 6 cMs. I currently have 28, 410 such cousins.
Also, you only get given 2 figures - amount shared and number of segments shared, not size of largest segment.
My closest is 723 cMs across 32 DNA segments, my most distant are all 6cMs across 1 segment.
If the latter has a very well researched tree going back as far as 7G grandparents on all
lines, I might be able to make an educated guess at the relationship. I haven't however achieved that on many of
my lines, so there are plenty of gaps, similarly in their tree.
If I can persuade them to upload elsewhere, I can see more information, can check them against other matches, etc, etc.
A 10 cMs match of mine, relatively small, is it genuine, is it not? Descended from the same family as me from Chitterne, Wiltshire, our mutual 6G grandparents, paternal side.
A 7.8 cMs/1 shared segment match at myheritageDNA, descended from this same family, same line as my Ancestry match but split off at their mutual 4G grandparent level.
Makes it more likely.
Can I persuade my Ancestry match to upload elsewhere - no, she can't work out how to do it, doesn't particularly want to do it.
Does my cousin share both these matches? - yes, lilely to be a paternal match.
Can I persuade anybody else to upload elsewhere? Yes, this family well represented in my Ancestry matches.
Does this person match anyone at myheritageDNA or elsewhere? Yes Eureka. But at only 6 cMs/1segment.
Do I ignore this because of only a 6cMs match?
No, I add it to my list of mounting evidence that we are all descended from Stephen Leversidge Leverstretch Leversuch from Mere and Chitterne, Wiltshire, and that he was indeed my 6G grandfather, something which had been only a (fairly strong) assumption before DNA testing came along.
To me, it is about building a case, regardless of size of match, and I rarely know what size segments I share with my Ancestry matches. Other than that below 12 cMs, by definition there can only be 1 segment, as they ignore segments under 6cMs.
Regards Margaret
