GedMatch vs Wikitree relationship

Question

I just took a look at my one-to-many GedMatch matches.  The second and third persons who match me with the most DNA  are found on Wikitree.  In the relationship finder on Wikitree with them, I am a 19th cousin once removed (total Cm = 95.7) to one and a 21st cousin twice removed (total cM = 103.9) from the other.  

Another Wikitree cousin matches me on a total cM of 80.1, and we are second cousins on the relationship match, which is also well documented with sources.

I don't understand this.  Can anyone explain it in simple terms to me?  How is this possible?

Answer 1

Probably something in your or the matches' trees on WT is missing or incorrect (at least biologically).

Answer 2

This is why dna trumps anything that wikitree claims.  This is also a clear case of why wikitree is unreliable.

Head over to dna painter and enter that cM and get the estimated relationships and then you will start to see how they should be relating in.

Comments

Took your advice to check the relationship with DNA Painter.  It appears the Wikitree relationship finder followed the paternal trail on the 19th cousin, but DNA Painter shows more of a connection on the maternal side.  Her mother is related to a lot of Bahamian people who are related to me although her mother and I have no direct relationship.

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FYI my comment was not meant to be ugly but to point out what wikitree has is not what happens with dna. It’s more of a guide. There could be multiple connections to an ancestor and you really have to deep dive into each match to understand the connection. Also overlapping connections is a thing as well.

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No problem. Thanks.

Answer 3

Perhaps the trees just don't include enough of their cousins to match in the way expected.  Probably because the individual is living. Expected relationship: 
38% chance Half 2C, 2C1R, Half 1C2R, 1C3R
30% chance 3C, Half 2C1R, 2C2R, Half 1C3R
20% chance Half 3C, 3C1R, Half 2C2R, 2C3R 

Answer 4

If you both have relatively complete trees, the answer is that someone (or more than one someone!) has an NPE somewhere; it would take some further investigation of where their lines intersect to discover who that's likely to be.

Answer 5

Carolyn,

I think the answer is in the Bahamas.

Looking at your tree, and the trees for Peter Adams and for D Cargle show the Bahamas. In your tree you have William Carey - son of William Carry and Margaret Knowles, all Bahamans.  The families are in the Bahamas all at in the same time frame.

Peter has a Carey line see Michael Carey - Bahamas

and D. Cargle has a Knowles line in Bahamas.

In addition you have a Carey cousin marriage in the Bahamas  and the Carey lines involved have not been extended.

So the simple answer is that there are common ancestors in the Bahamas likely with the names of Carey or Knowles - possibly both as the families seem to be intermarried.

 

Comments

Yes, I agree.  As I mentioned above, I found the mother of the "19th cousin" was related to a bunch of people from the Bahamas, but not a direct line relation to me.  I am sure we share some DNA through the Bahamian families.