Should we increase scope of Relationship Finder?

+9 votes
312 views

This question arises out of a question posted earlier.

http://www.wikitree.com/g2g/254497/how-can-find-the-connection-wikitree-used-for-dna-test-results

When adding the yDNA or mtDNA test and the connection goes beyond the 25th generation, there is no easy way to find the patrilineal or matrilineal common ancestor.  

I would suggest that the yDNA and mtDNA tests be shown within the same scope as Relationship Finder. This would mean that either the yDNA and mtDNA needs limitations added or the limitations of Relationship Finder expanded.

in WikiTree Tech by Ken Sargent G2G6 Mach 5 (57.0k points)

3 Answers

+7 votes
You don't need the RF for yDNA and mtDNA.  You just go straight up the male line, or female line.  No other cousinship is relevant.
by Anonymous Horace G2G6 Pilot (568k points)
The problem is that when someone else's yDNA appears on your profile, you don't know the common ancestor. That other yDNA cousin is relevant.  If I went straight up the male line, I would not know when to stop at the patrilineal Most Recent Common Ancestor.  If that person were a match, I would not know when to stop marking "Confirmed with DNA."

Also, Relationship Finder tells me that I and my yDNA cousin are not blood relatives, which is not correct.
A yDNA match extending back more than 25 generations? Wow! Can you tell the rest of us who the reported match is, so we can understand the question better?

I provided a link to the question that prompted this suggestion.

http://www.wikitree.com/g2g/254497/how-can-find-the-connection-wikitree-used-for-dna-test-results

A previous suggestion that would separate out the tests based on the connection direction the DNA testers profile hasn't yet received much traction. This would have told us the DNA tester was related to me via my father, etc. until I reached the profile in which the DNA Tester indicated the relationship was via a son. If this is implemented, then we could trace up the patrilineal line until we noticed the change.

Hmmm... The database relationship finder says your ycousin is not your blood relative. The database DNA Ancestor tool says that both my German Shepherds share my X chromosome. They are both marked as "non-biologic" as I adopted each from a breed rescue.   Seems like previous conversations had alluded to just these sort of errors occuring.
Hello Ken, you noted "The problem is that when someone else's yDNA appears on your profile, you don't know the common ancestor."

Let's assume you are http://www.wikitree.com/wiki/Weatherford-198 and the yDNA of http://www.wikitree.com/wiki/Weatherford-292 appears on your profile.  If you are at http://www.wikitree.com/wiki/Weatherford-292 then under DNA Tested  you see " Y Anonymous Weatherford -><- "  If you click on -><- then you will go to http://www.wikitree.com/index.php?title=Special:Relationship&action=calculate&person1_name=Weatherford-292&person2_name=Weatherford-198

There you find Martin Weatherford http://www.wikitree.com/wiki/Weatherford-112 who is their most recent direct paternal line ancestor and that is where you stop marking "Confirmed with DNA."

Peter, I was referring to the example in the original post.

"When adding the yDNA or mtDNA test and the connection goes beyond the 25th generation,"

In these cases, Relationship Finder tells us that there is no Blood relation so the common ancestor is not known.

Thank you.

It is my understanding that the 25 generation limit is due to server load.
+4 votes

I agree the Relationship Finder should be improved.  What I don't know is which improvements require too much server processing.

The Relationship Finder would be more useful if you had the option to  limit it to a direct paternal line relationship, or a direct maternal line relationship, or a X chromosome relationship.  What happens now is it provides the most recent relationship (among others) which may not be a direct paternal or maternal line.

The relationship finder goes back 25 generations.  WikiTree's earliest known Y-DNA or mtDNA tested direct lines are currently about 35 generations (see http://www.wikitree.com/index.php?title=Space:WikiTree_Tops#DNA )

It would be most helpful if you could enter up to five GEDmatch IDs at once and automatically see any shared ancestry.  The more tedious feature option (but also a great one) would be the ability to enter up to five WikiTree IDs at once and see any shared ancestry.

Sincerely, Peter

by Peter Roberts G2G6 Pilot (559k points)
edited by Peter Roberts
If we were able to have GEDmatch, DNA.Land, 23andMe, Family Finder, DNAgedcom's ADSA, or Kitty Cooper's Segment Mapper, etc, automatically link to the user's (shared) ancestry in WikiTree  then I imagine that would be the incentive needed to improve the Relationship Finder.

So I believe we need WikiTree users to encourage one or more of the above to allow automatic linking to ancestry in WikiTree.
+3 votes
I fear this would be a processing challenge, but I will put it out there anyway.  If we have done as much testing as we are able and are working diligently to maintain/clean up profiles is there *any* sort of duplicate search that would pick up on profiles and auto compare/suggest merges so the prevailing DNA could attach correctly?

Kits which have been removed should be timed out or hidden so we don't have false hope of a match.

Last logged in dates on some of the original profiles would be helpful to know when we try to match or merge where we are working as well.
by Elizabeth Townsend G2G6 Mach 2 (20.2k points)
If two profiles are connected to the same mother, ie showing as "siblings", any mtDNA tag will propagate to both of them whether they're identified as duplicates or not.

If they don't both show the DNA tag it's not because of duplication, it's because one of them has the mother disconnected.  The system can't help you through a missing parent.  You don't have to wait for a merge to connect duplicates as siblings.

Looking at it from the other side, if two duplicates have matching mtDNA tags, they must be already connected as siblings, and the DNA adds no further information about merge prospects.  All the siblings will have matching tags, and nothing tells you which siblings are duplicates.  Nor does it matter much.

Hello Ken, you said "... nor do  I understand why we can confirm with DNA the common ancestors for 3rd cousins."  I said "You can confirm both parents (i.e. the ancestral couple) of third cousins because there is greater than a 99% probability that both of them contributed a detectable amount of auDNA to all their descendants who are third cousins and closer to each other."  

As you noted the probability of no detectable auDNA between 3rd cousins is 2.3% which is not the issue.   The original point is why can we confirm both male and female of the ancestral couple.

Peter, The problem is that "Detectable" does not mean they are full third cousins, as you indicate.  They may be documented third cousins, but the DNA service may "Detect" they are a match but predict they are 5th cousins. In other words, if they are 1/2 third cousins, the DNA Service will detect they are a match but they DO NOT differentiate between full third cousins and 1/2 third cousins, or 5th cousins, etc.  You could get the exact same prediction for a full 3rd cousin as you would with a 1/2 3rd cousin.  

Because of this, you shouldn't confirm with DNA both, when the DNA doesn't know if both contributed.

This brings me to a numeric question.  Thank you for bearing with me on the learning curve here.

This reference is for what by traditional definition are 4th cousins.  If I understand the math right from Peter's post

Chr Start Location End Location Centimorgans (cM) SNPs
8 73,402,234 102,626,394 23.1 2,468

 Using this reference Peter provided above,
http://isogg.org/wiki/Autosomal_DNA_statistics#Table

cM half-
identical
(or better)          
Relationship
26.56                   Third cousins once removed

13.28                   Fourth cousins, third cousins twice removed

Simply by looking at the shared cM of 23.1 which is far closer to the Third cousins once removed than the Fourth Cousins, does that provide any insight regarding the contribution of the MCRA parent or pair of parents?    I am still trying to get my head around this and I don't know how to read the mito to see if there is any insight there.

Thank you,
Elizabeth

Actually, shared DNA tells you that two people descend from siblings or half-siblings, but it tells you zilch about the identity of the common parent(s), even if you do know which parent..  The parent(s) could be completely misidentified and the test results would be the same.

Or of course they could be Unknown Unknown and we could "confirm" that.
Hello RJ,

If two first cousins share the expected number of cMs for their relationship then is it your belief we should "not confirm with DNA" their shared grandparents?  Because it is possible the same postman twice rang twice ;-) ?
Please stop arguing in circles.  It's a common situation that you know who somebody's brother is, from a will, census etc, but you have only a speculative guess as to the identity of their parents.  The DNA does nothing to confirm that guess.  It only confirms that the brothers are brothers.

WikiTree has a lot of profiles with wrong or speculative parents who could be "confirmed" by DNA tests that actually have nothing to say on the issue.
Hello RJ,

There are indeed thousands profiles which are in need of cleanup - merging, bio writing, adopting.  Our new Error Reporting shows us just how extensive even the simple data point correction is to the health of the tree as well as the integrity of the data as a whole.

For those of us who are new to DNA Genealogy, we do not "argue in circles" to frustrate the rest of the community.   We are trying to learn a new way of doing things.  Many of us know how to source and have quite a lot to add to our lines within the tree, but get stuck working on fixing the "major" lines we attach to and spend time each week piecing back together.

We all have our own approach - it's the nature of a collaborative effort and exactly how a family works.  Good days, bad days, bumps and warts, we work through it because we love what it's about and we learn how to work with one another and help out when someone needs it.

ET
And now we've got loads of Confirmed flags that aren't justified by the evidence, so that's more junk to clean up.

WikiTree's current position is, if you find a DNA match, you can Confirm whatever tree you've drawn that links those profiles to a common ancestor, even if it's a load of rubbish.

Elizabeth, I had to chuckle a little when you wrote "we do not "argue in circles" to frustrate the rest of the community." It seems we agree that we do argue in circles but for other reasons. :)

Peter, I believe that RJ was referring to "Confirming with DNA" when before the relationship is "Confirmed without DNA". As I have pointed out repeatedly, the choice of terminology "Confirmed" is misleading, it implies something conclusive, which is how most people seem to read it. 

I believe that the "Confirming with DNA" as a result of yDNA and mtDNA those profiles that have not yet been "Confirmed without DNA" is common. 

I believe I read a response to a concern on another thread, that parent/child relationships exist without sources and the response was to keep the connection and let DNA resolve the issue.  The problem with this is obvious, you don't have to defend a claim, you now place the burden on others to prove the negative. It would take a significant number of tests to prove that a connection does not belong in most cases.

I believe the opposite problem is true for auDNA.  The predictions used by the DNA Services should be enough to defend a claim of a parent/child relationship that has already been confirmed without DNA in most cases, but recording this fact is being withheld because of the existing guidelines which IMO, adds nothing to the evidence that already exists for those profile up to but not including the common ancestors.

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