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General => Ancestral Family Tree DNA Testing => Topic started by: strictlysnoopy on Wednesday 15 February 23 13:02 GMT (UK)
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Hope somebody can help to clarify. I have a 4th-6th cousin who has discovered on Gedmatch that he and I share two chromosomes from my maternal side of the family. He has added them together together and says that he is now a closer cousin than first thought. Is he right?
Secondly, due to this new development he says that he is descended from my other great grandparents. I have always thought that inheritance of chromosomes from parents is random and therefore we have inherited a chromosome that other cousins have not but from the same ancestors. Am I correct?
Thanks
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First of all, how do you know that he is a 4th - 6th cousin? If that is a statement relating to your match by the DNA testing company, it is a suggestion based on the most likely ranges of probability for the length of the match between you, nothing more. The actual match could be closer or more distant.
Presumably the length of the overall match between you is also given by the testing company? Adding two chromosomes together (whatever that means - presumably the combined length of the matches between you on those chromosomes) doesn't in itself prove anything, particularly unless you or he has sufficient information to compare them with a chromosome by chromosome breakdown of other matches on the same line of descent. You or he could also have inherited segments on other chromosomes to the same ancestor, which are not shared between the both of you.
The match between you proves that you are related, unless it is at a lower length of less than around 15 cM or so, where there could be room for doubt. The overall length of the match between you can suggest a range of likely relationships and the probabilities for each of them, using a tool such as DNA Painter.
But the only way to definitively confirm the exact relationship is to methodically and robustly prove the lineage of both of you back to a common ancestor by research and evidence from documented sources that link each generation to the previous generation, and so on, until you can confirm where the two lines meet. The probabilities for suggested likely relationships given by the DNA Painter tool or a similar relationship estimator can be used to guide that research along specific avenues, but the paper trail is going to be the definitive proof of how you may be related. The DNA match initself proves nothing more than that you are related, not how.
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Thank you Phil, you have confirmed my conclusions with a comprehensive and wonderful explanation. We have well documented paper evidence that we have in common a Henry and Gwenllian Williams 2nd great grandparents for me and 3greatgrandparents for him. Ancestry for both our DNA results.
This latest fanciful theory of his annoyed me as it is ridiculous. Thank you again for confirmation.
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Out of interest, what is Ancestry reporting as the cM and segment details
ie as per this
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Ancestry results as follows
23cMs 3 segments
Unweighte shared DNA. 50cMs
Longest segment. 21cMs
It was Gedmatch that gave a two chromosome match between us. Sorry that is all I know as I find Gedmatch very difficult to use.
Thanks
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I find Gedmatch very difficult to use.
I'm not surprised, it's so complicated but you're ahead of me as I've yet to discover how to use it! ::)
Annie
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We have well documented paper evidence that we have in common a Henry and Gwenllian Williams 2nd great grandparents for me and 3greatgrandparents for him.
So you are 3rd cousins, once removed.
The mean shared cM for that relationship according to DNA Painter is 48 cM, with a range between 0 and 192 cM over 4514 submissions. 1,686 of those submissions were between 26 and 50 cM, and 2,826 submissions were at 50 cM or less.
At a match of 50 cM unweighted, you are pretty much on the mean value for shared cM at that relationship level. That in itself is not proof of your relationship, but it corroborates your documentary evidence very well.
It is notable that from an unweighted match across 3 segments, Ancestry's Timber algorithm has effectively stripped out over half of the unweighted match length.
The unweighted CiM tool at DNA-sci.com allows comparison between weighted match lengths (after Ancestry's Timber calculation) and the unweighted length or comparable figures from other testing sites that don't attempt to strip IBD segments. The stripped match length of 23 cM and unweighted length both suggest that matches in the region of 3C to 3C1R grouping are the highest probability.
For Ancestry's stripped length of 23 cM in particular, the tool suggests the highest probability (30.7%) for a 3C1R, Half-3C, Half-2C2R or 2C3R match, so I would be entirely happy with that as corroboration of your documented 3C1R relationship based on the paper research.
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Thank you Phil, much appreciated.
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Is there such a thing that determines maternal or paternal DNA,
Hope that isn't a daft question, have done a DNA but am none the wiser
Louisa Maud
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Not a daft question at all Louisa, but it is quite a complex one. There are two sex chromosomes, referred to as X and Y. All males have one X chromosome, inherited from their mother, and one Y chromosome inherited from their father. Females have two X chromosomes, one inherited from their mother and one from their father.
So a child can only inherit an X chromosome from it's mother, because females don't have a Y chromosome. But it can inherit either an X or a Y chromosome from it's father, because a male has one of each type. Which chromosome it inherits from it's father determines it sex.
Since the Y chromosome is only passed down the male line it can be used to investigate the direct paternal line. That involves taking a separate and more expensive test than the more common autosomal tests offered by Ancestry and similar companies.
A different type of DNA called mitochondrial or mtDNA can be used in a similar way to investigate the female line. It is separate from the nuclear DNA tested for autosomal matching, and is passed down by a mother to all her children, both male and female, but only the female children can pass it on to their children. So it can be used to investigate the direct maternal line, but the line will be broken if a mother only has male children. mtDNA tests are also more expensive than autosomal tests.
I wouldn't recommend taking either a Y DNA or mtDNA test unless you have taken advice and understand what you might get from them and whether they will be of any help to you.
That's the brief answer I'm afraid. I don't have much more than a basic understanding of either Y DNA or mtDNA myself!
I hope that makes sense. I'm typing this on my phone since my PC failed yesterday, and it's not so easy to keep track of what I'm typing.
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Many thanks Phil 57, it is a bit complicated for me but it does make sense, contradicted myself there I suppose
I don't think I will do any DNA tests, will stick with what I have
Hope your PC recovers
Many thanks for your explanation, it just might help others as well
LM
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One of my Great Grandmother’s on my Paternal line has no Father listed on her birth certificate.
The man her Mother went on to marry many years later was only 10 years old when my Great Grandmother was born so he can be discounted.
Searching the local Archives there are zero Court records.
Searching British Newspapers there is no trace of her Mother initiating any search or proceedings against the Father.
So I have zero paper trail for her, just her individual BMD, Census etc
Then a new reasonably high cM match gives a hypothesis that the match’s Great Great Grandfather may be the missing Father.
It took ten years before the DNA match showed up.
So I would not discount having a DNA test done, if there are no paper trails it is all there is, unless somewhere out there there are records still waiting to be transcribed and catalogued, either way it can be a waiting game.
Good Luck in your quest
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The reason I wanted to find out if there was a maternal and paternal separately was I am showing a small % East Europe, apart from my gt grandfather being Swedish, and it didn't show up as so I wondered where it came from, I am 94% English, the 6% is small smattering of Scottish, Irish and Welsh, my fathers parents were barges and although always shown as being born in London I haven't been able to get back further that 1800,
Thank you for your suggestions but will stick with what I have so far but it does intrigue me as to how these Tv progress come up with named fathers who prior to DNA were unknown and unamed
LM
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Is it correct to add two of the highest centremorgans together and then claim to be a closer cousin?
Thanks
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I would say no, but if your match wishes to assert that, then ask him to show how he believes you are related, and provide his evidence of a documented paper trail to support his claim.
I manage my brother's test. Obviously, as we are brothers, any matches that we share or each have are related to both of us in the same way. I could provide plenty of instances where I have a match to a cousin but my brother doesn't, and vice versa. We also have many matches where the amount of DNA that the match shares with each of us is quite different.
One example, a second cousin who matches me at 226 cM across 7 segments; largest segment 118 cM. The same cousin matches my brother at 131 cM across 8 segments; largest segment 40 cM.
As you have previously stated, you have a documented paper trail for your match as 3C1R. Your match is pretty much on the mean value for a relationship at that level. But anywhere between no DNA match at all to 192 cM could also be consistent with that relationship according to the cases used by DNA Painter.
DNA inheritance is random. You inherit about 50% of your DNA from each of your parents, as would a brother or sister of yours. But it doesn't mean that they would inherit the same DNA from each parent. You could theoretically inherit only 1% of you paternal GF's DNA and 49% of your paternal GM's. Similarly with your maternal grandparents. Your brother might inherit 49% of your paternal GF's DNA and only 1% of your paternal GM's. An extreme example, in practice the variances will not be as great, but with each generation that you go back the imbalance will likely increase as more GG parents, GG grandparents, etc. DNA is added to the mix and similarly randomly inherited from their parents.
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Thank you Phil, Really hope you plan to write a book.
Knew in my heart of hearts that it was not right, but he insisted. It’s a long time since O level biology ;D. When somebody is so insistent it makes you doubt ourself.
Thanks for all your replies I really appreciated them. Keep safe, hoping your computer is good to go now 😁
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Try YouTube for gedmatch
Mrs Zaph
quote author=strictlysnoopy link=topic=870283.msg7413541#msg7413541 date=1676499539]
Ancestry results as follows
23cMs 3 segments
Unweighte shared DNA. 50cMs
Longest segment. 21cMs
It was Gedmatch that gave a two chromosome match between us. Sorry that is all I know as I find Gedmatch very difficult to use.
Thanks
[/quote]
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Great detective work. On Ancestry are you parent 1or 2?
Gedmatch has so much info, but agree so difficult to navigate, esp for newbies 😁
Is your Gedmatch name the same as above? Will try my best to find you, could be messaging you before long 😂
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Family History Fanatics have the Youtube channel that Gedmatch links too for each tutorial related to each of the various tools available on Gedmatch
Plenty of visual resources there.
https://www.youtube.com/@FamilyHistoryFanatics
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Thank you
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All of this is very interesting but way above my head
Thank you
LM
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Thanks for all your replies I really appreciated them. Keep safe, hoping your computer is good to go now 😁
Unfortunately it seems to be the motherboard, which leaves me with a dilemma. Should I try to find a replacement (it's a rather old spec now, using older type RAM and processor) or do I stump up the money for new MB, processor and memory, and rebuild Trigger's broom into a modern machine?
In the meantime, I have acquired a docking station for my laptop at a good price and am up and running, having loaded my files from backups and connected it to my monitor and other peripherals.
If I can't find a suitable compatible MB, then rebuilding as an updated machine will have to wait a while, being a more expensive option :(
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O heck, sounds like a whole heap of trouble and headaches, esp with soaring prices 😡. We stretched our budget and bought a Mac book. Never regretted the decision. Had a few issues which the Mac shop repaired for free, as always the guarantee had just expired but little did we know they will repair most faults for free for life of the machine. They also run classes free for Macs, cannot fault them, in all ways.
Just completed my first multi DNA comparison tables, so pleased. Wish they would carry out this task the other way round, instead of ref no’s to compare compile a table of all your results using the chromosome you choose. Also the chromosome table they produced showed my parents were not related when infact they were, although distantly, I have the paper trail.
Thanks once again, you really should publish a book 😁
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Thanks once again, you really should publish a book 😁
I highly recommend "Tracing Your Ancestors Using DNA", edited by Graham S. Holton. It's my go to reference book and the contributors are far more knowledgeable than I'll ever be.
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Thanks for all your replies I really appreciated them. Keep safe, hoping your computer is good to go now 😁
Unfortunately it seems to be the motherboard, which leaves me with a dilemma. Should I try to find a replacement (it's a rather old spec now, using older type RAM and processor) or do I stump up the money for new MB, processor and memory, and rebuild Trigger's broom into a modern machine?
In the meantime, I have acquired a docking station for my laptop at a good price and am up and running, having loaded my files from backups and connected it to my monitor and other peripherals.
If I can't find a suitable compatible MB, then rebuilding as an updated machine will have to wait a while, being a more expensive option :(
Out of interest Phil, how old is your PC?
For a number of years now my PC has been totally obsolete, MOBO has a CPU socket that is no longer in use, the CPU is not supported by Windows 11 and the RAM is no longer available.
For some reason my wallet keeps hiding itself!!!!
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Out of interest Phil, how old is your PC?
For a number of years now my PC has been totally obsolete, MOBO has a CPU socket that is no longer in use, the CPU is not supported by Windows 11 and the RAM is no longer available.
For some reason my wallet keeps hiding itself!!!!
Which part ;D
I bought a desktop PC around 1994-1995 I think, replacing an Amiga 1200.
It has gradually had components replaced over time, but I would guess around 2010 that none of the original components remained, so I suppose it could be considered a different machine from that point on.
It has a Gigabyte ATX/AM3 motherboard with an AMD Phenom II CPU, both bought in October 2011, along with two 1TB HDDs.
About 18 months ago, I moved the system partitions onto a 1TB SSD and doubled the memory to 32GB as DDR3 DIMMs had become quite cheap. It gained quite a performance boost from that, as it had become rather sluggish.
Although the CPU isn't on Microsoft's Win 11 list, the readiness checker doesn't complain about it, but the insurmountable problem is the lack of a TPM module, and the inability to install one that meets the requirements.
Not that I'm in any rush to "upgrade" to Win 11, I've only been using Win 10 as my primary OS for about a year!
Using my laptop (Lenovo T450/Win 10/Intel i5) in a docking station has made me realise that I can get along quite happily with a moderately powered PC. It also has an SSD though, which again seems to be the best performance upgrade for the money, compared to the speed of HDDs. Samsung 1TB SSDs can be had for less than £60 now.
Anyway, I managed to locate a suitable AM3/DDR3 motherboard today, with the required number of SATA and USB headers, so hopefully it will be up and running again before long.
My wallet generally behaves very similarly to yours ;D ;D ;D
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Thank you, much appreciated.
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Is there such a thing that determines maternal or paternal DNA,
Hope that isn't a daft question, have done a DNA but am none the wiser
Hi Louisa,
Ancestry seem to be able to distinguish between paternal/maternal sides as long as you have a tree with your parents added with possibly g/parents too?
It's quite a new thing but seems to be working for me so far although I have quite a big tree to help them help me ;)
Annie
Annie
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It is a developing algorithm, so probably best to expect changes.
What I find odd is that I see in Unaccounted, some of my DNA Matches who are already in my Tree, where their relationship is flagged as is which side of my family they belong.
So to me at present it is questionable.
Where it has assigned I have gone through a couple of hundred matches on each parental side and it does look as though they are correctly assigned