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General => Ancestral Family Tree DNA Testing => Topic started by: Alan of Kaslo on Thursday 23 November 23 23:14 GMT (UK)
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Hello.
I had some really good luck getting my DNA done. First thing I found was a very close relative that turned out to be a first cousin. Turns out our mothers were sisters and the lifelong mystery of who was her father was solved. That opened up a big part of my mother's family tree which was nice.
On my father's side ... the man on his mother's birth certificate had actually been dead 10 years before her birth. Her real father was another complete mystery. Nothing really popped out on the DNA match screen the way it had on my mother's side.
My 2nd cousin ... the son of my my father's sister's daughter ... took the same type ancestry DNA test. I see him top of the list as a match. I use him to compare to potential matches that I have.
Here's my question. I noticed at a certain point if you go back he will not show up as co-related to people who are related on my father's side. I believe it takes going back 7 generations and then this cousin does not show up in my thru-lines.
I found what a bunch of clues that seem to point to an individual on the DNA match screen being a relative of the man who fathered my grandmother. But ... my cousin does not show as DNA-related to this person. I count the generations between this person and the potential parent and it's 4 (after him the potential parent is the 4th).
I'm wondering if the 4 generations plus the fact that i'm comparing to my father's sister's grandchild would have a water-down effect? Making it so he might not show up as co-related.
Sorry for explaining it so bad.
Any help greatly appreciated!
Thanks.
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It is very possible, DNA is not inherited in a predetermined order but by a random process called Recombination.
By going back four generations it is very possible that from that Ancestor you (or any Cousin) inherit no DNA.
Your Ancestry test did not analyse your whole DNA, just about 7% so you should see how variances can happen.
At 3x GGP level with equal DNA inheritance you will only have c3% of that 3xGGP’s DNA.
As an example I have a 364cM match and yet two of their first Cousins each share 115 & 95cM respectively with me, such is the randomness of DNA inheritance.
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Thanks. That was helpful.
I won't automatically disregard this person just because my cousin is not showing as related to them. I was ready to do that before making this post.
The person i'm curious about tests in at about 40cm and another known cousin has 32cm. This cousin is the great grandson of my great grandmothers brother. But now that i have learned from you about the randomness of how the DNA is passed down I don't think it's as easy to compare as I had thought.
Thanks again
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I heard it described once as a stew. We all have a bowl, but I have a bit more beef than carrots, you have more celery than beef and sister Mary is the only one got mushrooms, but we all got our stew from the same pot.
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It is very possible, DNA is not inherited in a predetermined order but by a random process called Recombination.
By going back four generations it is very possible that from that Ancestor you (or any Cousin) inherit no DNA.
Your Ancestry test did not analyse your whole DNA, just about 7% so you should see how variances can happen.
At 3x GGP level with equal DNA inheritance you will only have c3% of that 3xGGP’s DNA.
As an example I have a 364cM match and yet two of their first Cousins each share 115 & 95cM respectively with me, such is the randomness of DNA inheritance.
I know virtually nothing about DNA, except that I am told I looked like my late Mum and the family Dentist said our teeth looked similar, etc.
US National Library of Medicine
Recombination
https://www.ncbi.nlm.nih.gov/books/NBK26898/
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I saw this image in an article which shows how random DNA inheritance can be.
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Unknown parentage, half cousin relationships and big age gaps in a generation can cause some really odd looking results at times. I've had a few in the last couple of weeks in the 20-30cM range suggested as 4-6 cousins but I'm pretty sure their grandparent has also tested and is my half 2c. It all fits according to bmd, they read but won't reply to messages and confirm the grandparent theory or shared cM to others. It's either another dead end or a case of me going it alone buying certs and diving into their social media.
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Biggles that's a great image id like to copy it
Alan when you say your 2nd cousin doesn't show as a match do you mean he doesn't show as a shared match
I manage my.mothers my paternal.aunt's and nephews DNA results sometimes the distance matches ( usually under 20cm) too small to show on shared matches
But if I go into their individual accounts the person does actually show as a match
Another Example I looked at my.mothers shared matches to a Welsh relative my nephew didn't show on her shared matches
But when I compared my nephew's results to the person not only did he match 25cm bot on his shared matches my mother+ myself showed up
Occasionally a younger generation gets a higher match.
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My cousin shows up fine as connected to me.
This cousin is grandson to my Dad's sister. So right away he is watered down a bit. The person I was trying to compare DNA with was about 4 generations back. I'm related 40 cm's to this person's relative but my cousin doesn't show up as co-related. Before I made thread I had assumed any potential father to my father's mother would have to be related to my 2nd cousin... which is a wrong assumption, apparently.
The thing I kept forgetting beyond this new info is the fact that this cousin is through my Dad's sister and from a daughter of hers even. That has to have some diminishing effect on DNA you would think.
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Through Roots Chat I met a 3C in 2012.
We eMailed each other fairly regularly and kept in touch to help each other out with the family line that was common to us both.
Our Common Ancestor was my Great Great Grandmother, who was a bit of a lass with her favours so much so she had at least three children out of wedlock to different Fathers (her Sister had two).
I am a DNA match to one of her Sister’s descendants and to others via a MRCA beyond my GGGM.
I met my 3C for the first time earlier this year before she passed away and we brought each other up to date on family research. Alas even though she had taken a DNA test I was not showing as a match to her, nor was she seeing any of my Shared DNA matches in our GGGM’s line nor any DNA Matches in the line of the man our GGGM married.
Such is the spanners DNA can through up, she has all the paperwork but DNA does not show any matches in our Common Ancestor’s line.
Again this is another image I have posted before and it shows how one can not inherit DNA from a specific xGrandparent. The image is only valid for the person to whom it is applicable, we each will have our own version.
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Thanks again for the comments! Really enlightening.
I thought I'd post a visualization of what I'm going through here.
The first panel is the distant cousin i'm related to on ancestry. His great great grandfather is the potential father of my grandmother. All clues point to it but the distant cousin does not show as DNA-related to my 2nd cousin who also took a test.
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Here's me for comparison:
What ancestry says about me and the distant cousin:
You and
4th – 6th Cousin | Parent 1's side
Shared DNA: 39 cM across 2 segments
Unweighted shared DNA: 44 cM
Longest segment: 27 cM
In your experience ... is it possible that a person could have this type of DNA-match and share the same great-great grandfather? Now that I look at again, it seems that this person would be my great grandfather and this distant cousins great-great grandfather (one additional generation).
I had assumed the DNA cm's would be higher... but I have been mistaken about a lot of DNA so far.
Thanks so much for any help.
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Last piece of the puzzle.
My 2nd cousin's tree for comparison. It seems like he should show up as a match to the relative of "potential father". It's not too many gens back... but I don't know much about this DNA business. That's why I posted here and see what you kind folks think of the likelihood.
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Can I park your actual Cousins for now.
What I suggest is you build a new tree based on the DNA match and look at the Shared Matches between you, and try to build them into the tree.
When you have a few DNA matches in the tree export it to a Gedcom file.
Whilst you are building the tree take time out to learn about DNA Painter’s WATO tool. For what I suggest it that you upload the Gedcom file and complete the WATO analysis.
It may help in determining where the link is likely to have occurred.
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If you check the dropdown list of relationships/probabilities by clicking the shared cM on Ancestry there will be something like 25-30 possible relationships ranked from most to least likely.
The majority of them will be variants of full/half 2nd and 3rd cousins, it would be perfectly normal for the top two most likely groups to have almost the same probability as each other.
Those in the 4th-6th cousin range will be far fewer in number and likely to have a much lower probability percentage.
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Thanks for the help. I'll keep looking into things and follow some advice from here.
Cheers.
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Small update. I spent a few days poking around in thru-lines looking carefully at various connections. I started noticing things I hadn't seen before ... basically everything we discussed in this thread. I saw many examples of the randomness of DNA being passed down.
I saw people 4 generations back with almost double the cm's of someone 3 gens back. I saw multiple people all related to the same grandparent and the same number of gens from that person with completely varying amounts of DNA and some were connected to this cousin I keep speaking of and others were not.
I found a scenario where a related person was 3 gens away from a set of grandparents ...he was related to a sibling of my g grandmother (same setup as what I have been trying to compare to) and he had 38cm DNA whereas the connection I was comparing to had 40cm.
None of this really gets me any closer to knowing if this individual was my great grandfather ...but I now know it is a possibility. Rather than disprove the possibility in fact looking at the DNA does the opposite. He could conceivably be my g grandfather but now I need more clues to prove. I'll keep at it.
I'll have to keep looking into things. Thanks for sending me on the right path!
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Your Ancestry test did not analyse your whole DNA, just about 7% so you should see how variances can happen.
Note that Ancestry does not test your whole DNA, but it is comparing the same area of DNA that is in fact less than one percent of your DNA (not 7) between you and another person. All humans are over 99% identical - this part is ignored completely!
Eg. you and your child will share "50% DNA" (of that 1%).
By the way the son of your father's sister's child is your first cousin once removed (1C1R), not second cousin.
See the possible variations here
https://dnapainter.com/tools/sharedcmv4