DNA Confirmation Help [closed]

+9 votes
387 views

Let me just start by saying I know absolutely nothing about DNA so I apologize in advance if I sound like a Kindergartener.

Ok.  So, Alfred Hudson was my 2x ggf (Alfred,Alton, Betty, Ray, Me).  I just got a match to a second cousin: his grandmother was Alfred's sister, Mary Ella (Mary Ella, daughter, son).  So, to me, this is confirmation of not only the Hudson match, but also a match on down the line from Alfred to me.  Am I right?  Is this enough to be able to say DNA confirmed?  If anyone wants to check our Gedmatch ID's I would love it!  But, I prefer to give them in a private message as it is not just my own to be given out.Thank you in advance for helping this DNA infant!

Also, here is some of the comparison info

Largest segment = 26.2 cM
Total of segments > 7 cM = 97.0 cM
Estimated number of generations to MRCA = 3.6
633566 SNPs used for this comparison.

Our total shared cM=103.5

His WikiTree profile

Summer

WikiTree profile: James Smotherman
closed with the note: No longer needed
in Genealogy Help by Summer Orman G2G6 Mach 8 (85.8k points)
closed by Summer Orman
Texas logic for ya cousin...

"Those will have that coming to them when they get there"

Or IDK :) My test should be back in 4-5 weeks now :)
Hi cousin,  you ARE a character.  :D

4 Answers

+4 votes
I think such a result is a confirmation of sorts, but not a proof.  That's why the rule here (if I've read it right,) is that you need two or more such connections to "triangulate" the tests and be able to put the DNA confirmed sign on a profile.  The thing is that a match like that is a sure sign that there is a connection, but no guarantee that the connections is the one you hope and think it is.  I just recently started paying attention to the matches the test I took a good while ago.  They give me great confidence in several lines; 3-4 on my mother's side and one on my father's, but I need to get more experience before I claim anything as confirmed.  I think Ancestry.comDNA's circles are an attempt to help create proof.  But it's still in BetaTest so while there appears to be enough material for a line of my Conrads, I need to read a bit more about the basis for these things before I embrace the connections. totally.
by Dave Dardinger G2G6 Pilot (406k points)
Hi Dave,

I didn't use Ancestry circles, the match didn't even show up in Ancestry actually.  It first came through FTDNA, then we ran a gedmatch comparison.  Based on our known family lines (with solid sources, including birth/death/marriage certificates/census records/etc), I have absolutely no doubt.
Well, I don't have doubts either, but hanky-panky within a family is not unknown and could result in a match, but not to the person you think.  That's why the guidelines are conservative.  It''s kind of like the "should I eat this mushroom?" question.
Ha!  Back away from the shrooms!
HI Dave and cousins John and Summer!

We shouldn't confuse "matches" with the DNA Choices of "father is confirmed with DNA" and "Mother is confirmed with DNA"  A Match is almost certainly a blood relative in the predicted range for most people.

But the DNA choices mentioned above does not mean DNA has confirmed the person named in the profile is father or mother, it means that DNA further supports the person named in the profile is the father or the mother.

Checking off "Confirmed with DNA" does not exclude the possibility of hanky panky.
+5 votes

To confirm without triangulation your relationship to the match needs to be at, or below, the 3rd cousin level.  According to ISOGG:

0.781% 53.13 Third cousins, second cousins twice removed Degree 7

http://www.isogg.org/wiki/Autosomal_DNA_statistics

http://www.wikitree.com/wiki/DNA_Confirmation

→ → Is the autosomal match predicted to be a third cousin or closer?

2.a.) Yes

If the match for your Family Tree DNA Family Finder, 23andMe, or AncestryDNA test is predicted to be a third cousin or closer skip to the next question.

2.b.) No

If the match is beyond a third cousin, click here: Autosomal Triangulation. Note that a third cousin once or twice removed is beyond a third cousin.

If you and your match are both men also see X-Chromosome Confirmation.

by Kathleen Heath G2G6 Mach 2 (20.6k points)
Hi Kathleen,

A big TN howdy...

I've read all those instructions and I think confirmation is okay, but I want validation I guess. I don't want to anger the DNA leaders! Ahem...Kitty, Peter...if one of youse fine leaders want to chime in, I'd love to hear your take too.
Leaders wrote the instructions with input from the DNA project.  Big discussion in G2G last month.

I was really hoping someone else would have commented on the x Chromosome.  

IMO, you should wait to see if the guidelines change. The "one-to-one confirmation" does not involve the gender of the test takers. It involves having a single male descendant of the Most Recent Comment Ancestor(s).

If you and your match are both men there is a special opportunity for one-to-one confirmation if you match either on your X chromosomes. Since men have only one X chromosome, no triangulation is necessary"

I did yesterday but somehow it didn't get posted.

What I  think I wrote was that .

 I match with a male ('Fred') on the X chromosome. The paper trail confirms the necessary pattern of inheritance  ie from mother to sons and then  to daughter(s ), no two males in the chain. 

(ie   Supposed  Female Common ancestor, son, dau, dau,  dau , dau, me, and  Supposed Female Common  ancestor, son, dau, dau, dau, son, dau, Fred )

My son had a 50% chance of  inheriting  that particular X chromosome    If he did then he will also match this match but  I can't see how it alters the position.  Similarly if I my match was with the testers mother rather than Fred.

(actually I think that  I have read there is evidence that the X chromosome doesn't recombine as frequently as the autosomes with the whole chromosome being inherited unchanged in a significant number of cases .This may result in larger segments being retained over more generations which adds another variable )

Helen, your example presupposes the common ancestor had two sons, but what if they only had 2 daughters. The wikitree guidelines tell us that it doesn't matter if the Common Ancestors had only 2 daughters.  The guidelines tell you that if the DNA Testers are male, you can make a one to one connection, but this is not possible.  

If you or your matches are related via a son of the Common Ancestor, then it doesn't matter if the DNA tester is a male or female. The wikitree guidelines tell us that this only works for males.

The evidence about xDNA is that it is not very useful for calculating genetic distance.  Your son might receive the entire x chromosome from your father, or none, or some. He might receive the entire x chromosome from your mother or none or some.  

The gender of the children of the Most Recent Common Ancestor determines if a one to one relationship can be determined, not the DNA Tester.
+3 votes
Hey Summer!

I can't find your respective Gedmatch numbers, but based on what your said - you and James know your common ancestors (your Hudson great-great-great-parents and James's Hudson great-grandparents).  If I am reading this correctly, then you and James are second cousins - 2 X removed.

Given that you have a paper trail showing that you are second cousins - 2 X removed, if we look at the average expected range for second cousins - 2 X removed, which is 53.3 cM according to the ISOGG Wiki page:

http://isogg.org/wiki/Autosomal_DNA_statistics

your 103.5 cM is well within the expected range.

There are two things you want to do to support this strong DNA evidence.  First, if possible, you should check your respective trees to see if you have any other possible common ancestors - at least going back to your respective gr-gr-gr-grandparents.  If you can reasonably rule out any other possible common ancestors, this is strong supporting evidence.

Second - if you can find another descendant of the same Hudson line who might share any of  the DNA segments in you and James's 103.5 cM, this would allow you to demonstrate "triangulation" in the form of 3 or more descendants sharing common DNA segment(s).

At the very least though, this is a very promising DNA match that could help you identify additional relatives in your Hudson line.
by Ray Jones G2G6 Pilot (153k points)
+2 votes
As Ray has explained, it sure looks like you've confirmed your relationship with DNA.

Errm, maybe not. He's more distant than your first post indicated.
by Ellen Smith G2G Astronaut (1.1m points)
edited by Ellen Smith
How is he more distant? The lines are quite clear and very well documented on paper in addition to the DNA. Sorry, I don't understand?!
Sorry, I was comparing family trees on my smartphone. Not such a good idea!

Indeed, you two are second cousins twice removed. You're good!
Thanks Ellen! Okay, I'll confirm it! Thanks everyone for your help. I did give Ray our GEDMATCH IDs so he could run a comparison, since he clearly knows more than me!

Hey Summer!

Your Gedmatch results definitely fall in line with supporting a second cousin - 2 X removed relationship:


Minimum threshold size to be included in total = 700 SNPs
Mismatch-bunching Limit = 350 SNPs
Minimum segment cM to be included in total = 7.0 cM

 

Chr Start Location End Location Centimorgans (cM) SNPs
2 10,258,919 16,463,672 12.4 1,633
10 115,525,589 123,193,911 13.0 2,159
12 61,880 7,771,818 20.9 2,382
13 17,956,717 29,628,485 24.5 3,479
17 35,904,973 60,784,375 26.2 4,837

Largest segment = 26.2 cM
Total of segments > 7 cM = 97.0 cM
Estimated number of generations to MRCA = 3.6

Thanks Ray,  I already confirmed it....The match was quite strong and we have an excellent paper trail to back it up!
You have 5 substantial DNA segments in common for a total of 97 cM shared.  97 cM shared from viable DNA segments is strong evidence in support of a third cousin (or in your case, second cousin - 2 X removed) relationship.

Again - you still want to check your respective trees for other possible common ancestors back to your gr-gr-gr-grandparents (and it sounds like you have already done this - so you are good), but 97 cM shared supports your relationship.

So, another interesting thing I found out today. Alfred's sisters (Sarah and Mary) married brothers (James and Edward). My newly discovered cousin was a double cousin himself - he shared DNA with both of Alfred's sisters, Alfred too....here's an article about my ggg aunts' husbands...whose mother, as it happens, married again after the death of their father (not a Hudson) , to ANOTHER Hudson cousin. Man, this just keeps getting wilder!!!

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