Can I get help understanding DNA triangulation in this particular case?

Question

I've been in contact with another WikiTreer who may be related but is seeking some additional confirmation of the link. According to the tree as it stands, our most recent common ancestor is my 4X great grandfather who is her 5X great grandfather. She and her first cousin have both done DNA, and checking gedmatch, I found the following triangulation:

A and B

Chromosome 1 from 212,699,021 to 214,699,571 (3.0 cM's and 188 snp's)

A and C

Chromosome 1 from 211,953,732 to 214,909,158 (4.4 cM's and 334 snp's)

B and C

Chromosome 1 from  212,162,491 to 214,699,038 (3.8 cM's and 417 snp's)

I know that these segments of DNA are not large enough to show up unless you play with the variables on gedmatch, but we are talking potential 5th cousins, once removed here, not anything closer.

Do these matches suggest such a connection? Or is this just random noise I've picked up?

Answer 1

Those small segments don't suggest anything.  That doesn't mean that they might not be from your common ancestors, but with them being so small, they aren't indicative of nor suggesting anything.  Unless you can locate a triangulated group sharing 7+cM on a segment, all you can go off of is the paper trail (and its strength) to be confident of the shared ancestors.

You might find this link interesting:  https://isogg.org/wiki/Autosomal_DNA_statistics#Identical_by_descent_segments

Comments

Thanks Darlene!