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General => Ancestral Family Tree DNA Testing => Topic started by: History Lives on Sunday 06 June 21 15:03 BST (UK)
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This is a question I've started wondering as all of the DNA matches I've managed to have a look at so far that have the predicted "Common Ancestors" leaf next to them and the "You may be related through __" have been for people related through 5x great grandparents or closer, which is the same as ThruLines.
Is this the limit or has anyone else found one that gives a predicted ancestor more distantly than that? If not, I assume this is a limitation of the algorithm and not a genetic limitation as I have a suspicion a few of my matches are from a more distant connection than that.
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have a look at this diagram on DNApainter and you will see that it confirms that in most cases that is as far back as you can go
https://dnapainter.com/tools/sharedcmv4
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have a look at this diagram on DNApainter and you will see that it confirms that in most cases that is as far back as you can go
https://dnapainter.com/tools/sharedcmv4
I didn't mean in terms of centimorgans, but in terms of the actual algorithm that shows who your common ancestor is if both of you have this person in your tree. I know for a fact I have people who I'm related to further back showing up on my match list but the common ancestor feature isn't working for them.
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Ancestry only goes back to 5th ggparents. What is somewhat annoying is on the new feature where you can say which side a match belongs to, mother or father, I have several who are 5th cousin once removed so I add them as Distant Relationship and write the correct relationship in the note. In every case Ancestry has changed this back to their suggested 4th-6th.
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I have a 6cm.match which goes back to 6x ggparents
I know this because they are my mothers 5 x ggparents and show up on her thru lines
Im just going to check dates
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I think the answer to your question is that the label "common ancestor" as used by Ancestry means someone for whom they have established a (possible) Thru Line.
So Ancestry will only label a match as a common ancestor up to 5th great grandparents. You may be able to figure out more distant matches, but it won't label them common ancestors, even after you add them to your tree.
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Thats interesting my mother has a 6th cousin showing up on her thru lines at 11cm
So if he doesnt have enough dna cm to match me he wont show up ??
Now a younger generation are testing we also get 4th cousins twice removed
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If I understand it correctly (and it is perfectly possible that I don't) the thru lines and common ancestor label go together. IF a match were further back than that yet still had enough shared dna to pass the minimum threshold for Ancestry, it would still appear as a match, but will never get the "common ancestor" label.
The same goes for shared matches - I have two matches, both of whom I have traced, and who, having chatted to one of them, I happen to know are in fact brother and sister. Yet although both appear as matches, neither appears as a shared match with the other, since the shared dna is below the threshold set by Ancestry.
In the case of your mother's 11cm match, the chances are that one more generation down he will be below the minimum to even show as a match, not to mention a common ancestor - but of course the problem with random things is they are, well, random, and it is possible you actually share that same 11cm segment (unlikely, but possible) so he still might show for you as a match at least.
But if he is a 6th cousin of your mother, he is your 7th cousin, so he won't show on your thrulines ever, and if I am correct, then he won't ever show a common ancestor label either. To be fair to Ancestry, that's one of the reasons they recommend people get any elder relatives they can to test. (Of course, the cynical view would be that it also generates more money for them.)
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Thru Lines is only making a guess based on what it considers to be matching ancestors found in two or more users trees. Of course the assumptions made by Thru Lines rely on the information in those trees being correct. It may well be, but the not insignificant number of trees with errors in them that I have discovered on Ancestry makes me very wary of accepting any such indications as gospel without carrying out my own research on both connecting lines to prove or add support to the assumption. Too many trees on Ancestry seem to quote other Ancestry users trees as the sole source for corroboration, and there have been quite a few occasions where I have followed links on a particular individual through 20, 30 or more trees to find that no-one has a definitive source of proof - they seem to have just accepted an Ancestry hint or what another tree has told them without any thought or investigation :(
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Thru Lines are a form of hint - and are as reliable (or not) as every other hint.
Like every other hint, they can be both enormously helpful or frustratingly misleading.
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I agree you always have to check thru lines with documents
I have some relatives where different thru lines are possible because 2nd cousins in small villages married so we are related to both sides
I think ancestry prioritises thru lines from the ones that have the most documents and numbers of connections ..whereas I'd like to see the more obscure links
In the same way looking for a person on family trees the trees with most records are computer generated first
So if the information is wrong it's perpetuated by being copied by more people
Having said that thru lines have been able to confirm matches for distant relatives . One lady named her son after one man but named another as father on birth record ...DNA showed matches with thru line to the family whose surname he had as a middle name !
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I have three matches who appear (all three of them) on not just two but three thru lines through three different common ancestors.
The slightly horrifying thing is I rather suspect all three thru lines are correct for all three matches.
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I've been in a similar situation. It essentially makes grouping matches via colour coding impossible for those lines.
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I have a 10cM match with a person who Ancestry flags up as us having a common Ancestor and correctly predicts he is my 5th cousin once removed. Shared ancestors are my 4 x great grandparents and his 5 x ggp.
I also have a 10 cM match with his son, but Ancestry is not flagging up that we have common ancestors, because the shared Ancestors are his 6 x great grandparents - too many generations for Ancestry's algorithm.
In both cases the individuals are correctly linked to an extensive tree
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I have a 10cM match with a person who Ancestry flags up as us having a common Ancestor and correctly predicts he is my 5th cousin once removed. Shared ancestors are my 4 x great grandparents and his 5 x ggp.
I also have a 10 cM match with his son, but Ancestry is not flagging up that we have common ancestors, because the shared Ancestors are his 6 x great grandparents - too many generations for Ancestry's algorithm.
In both cases the individuals are correctly linked to an extensive tree
Would be great if they expanded this out at a later date; thankfully, most of my brick walls are now further back than this. Interestingly though, the shared surnames feature seems to work back to the 1600s (possibly 1500s?).
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Using the shared surnames I found a cluster of 9 Americans, from 23 cMs down to 10 cMs, descended from Cornelis Pieter Jongewaard born in the Zaanstad (Netherlands) 1641. The ancestor of the cluster left for America, mine remained in the Zaanstad and my father came to England in WWII. So it does seem you can go a long way back, in certain circumstances.
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I actually have 9 6th cousins show up by common ancestors, most (all?) of whom appear to be genuine, some up to 14 cM
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Using the shared surnames I found a cluster of 9 Americans, from 23 cMs down to 10 cMs, descended from Cornelis Pieter Jongewaard born in the Zaanstad (Netherlands) 1641. The ancestor of the cluster left for America, mine remained in the Zaanstad and my father came to England in WWII. So it does seem you can go a long way back, in certain circumstances.
Did Ancestry flag this group up as having common ancestors with you? Or did you find them by your own research?
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I just "lost" a Common Ancestor match yesterday. He was originally shown as my 5th cousin once removed. His 5th gg-mother being shown as sister of my 4th gg-mother, so the shared ancestor were my 5th ggparents and his 6th ggparents.
However his 5th gg-mother was actually the niece of my 4th gg-mother, (there being a 19 year difference in age between my 4th gg-mother and her oldest brother). So the shared ancestor was still my 5thh gg-parents but now his 7th. As Ancestry only goes back to 6th gg-parents, he dropped off my common ancestor match list. Don't know what has happened to all the other tree clones which erroneously show the two ladies as sisters and not correctly as aunt and niece. I counted up to 20 then gave up. Clearly the "sister" was a remarkable lady giving birth to three children after her death!
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I dont understand replies 11 +12
Why is it horrifying to have 3 Different thru line links to same person
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Why cant you add two and more colour codes to the same person
Or have i misinterpreted ?
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Why cant you add two and more colour codes to the same person
You can, but what I mean is normally I would look at the Shared Matches between me and a match with a known relationship, i.e. I know we have the same 2x great grandparents or something, and I would colour all of those shared matches with the same colour code. You can't do that in a community with high levels of consanguinity (inbreeding) because you can't assume they are related along that line, because they could be related along a different line, or both, and you have no way of assuming this unless you know for sure and both of you have detailed trees, then you could colour code and add multiple colours if necessary.
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Thanks history lives
That makes sense i have that problem on the side of a jewish great grandfather i think its called endogamy when related families inter marry
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Yet is is clearly possible to get back over 500 years or more. If it wasn't then the allegedly DNA tested skeleton of Richard 111 could well be a fraud, and attempts to isolate Royal remains at Winchester from the bones jumbled by Cromwell in the 17th century likewise.
Anyone enlighten me please?
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Yet is is clearly possible to get back over 500 years or more. If it wasn't then the allegedly DNA tested skeleton of Richard 111 could well be a fraud, and attempts to isolate Royal remains at Winchester from the bones jumbled by Cromwell in the 17th century likewise.
Anyone enlighten me please?
The Richard III false paternity issue was from looking at YDNA, which passes from father to son along the Y chromosome, and not using autosomal testing, which is your bread and butter genealogy test.
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Yet is is clearly possible to get back over 500 years or more. If it wasn't then the allegedly DNA tested skeleton of Richard 111 could well be a fraud, and attempts to isolate Royal remains at Winchester from the bones jumbled by Cromwell in the 17th century likewise.
Anyone enlighten me please?
Wasn't it a case that the test done for Richard III's descendants was much more specific for example it was only tracing the female line, and then an anomaly on that line and other facts like that. Yes we could all have tests done like that but they would cost a lot more and you would be ruling out 99%+ of people straight off by taking such a test.
In short they are highly specialised tests for specific questions to be confirmed or refuted.
(Well that's my understanding of it)
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I dont understand replies 11 +12
Why is it horrifying to have 3 Different thru line links to same person
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Why cant you add two and more colour codes to the same person
Or have i misinterpreted ?
The "horrifying" was a joke.
My maternal line were miners. There appears to be a very, very high level of families inter marrying within a relatively small group. (To give one example, I have one case where of six children that a couple had, 5 of them married their first cousin.) I assume this is related to the "serf" status of miners up until 1799, although it seems to have carried over well into the 19th and even early 20th century.
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Yes Richard 3rd was tested thru a maternal connection male descendants were all eliminated as would have been threat to the throne .
I went to a couple of talks by the leader of the dna team
It involved taking tiny bits of his teeth to specialists in other countries .
Maybe bone DNA is more stable than spit & swabs but less accessible for general public to extract
.i.ll raise the question next time !
As far as ancestry is concerned before the 8cm cut of limitation I had a thru line to a match of 6cm ...think it was linked to 4x ggparents
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Albu i suppose that is quite dangerous if the first cousins then went on to marry their first cousins from those 5 unions
But if they developed any family health issues how would you know if consanguinity or life conditions had affected them .
Not as bad as Egyptian royalty marrying their siblings !
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It involved taking tiny bits of his teeth to specialists in other countries .
Maybe bone DNA is more stable than spit & swabs but less accessible for general public to extract
.i.ll raise the question next time !
It might be worthwhile asking the dentist for the tooth next time you have an extraction!
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Albu i suppose that is quite dangerous if the first cousins then went on to marry their first cousins from those 5 unions
But if they developed any family health issues how would you know if consanguinity or life conditions had affected them .
Not as bad as Egyptian royalty marrying their siblings !
There is a lot of inbreeding on my mother's side, her family came from a farming village (Lode) near Cambridge. I was told that providing there are no underlying health issues this is quite helpful to family historians as you get a double dose if there are cousin marriages. If there are health problems it is very serious.
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Using the shared surnames I found a cluster of 9 Americans, from 23 cMs down to 10 cMs, descended from Cornelis Pieter Jongewaard born in the Zaanstad (Netherlands) 1641. The ancestor of the cluster left for America, mine remained in the Zaanstad and my father came to England in WWII. So it does seem you can go a long way back, in certain circumstances.
Did Ancestry flag this group up as having common ancestors with you? Or did you find them by your own research?
I found them by my own research. Peter Calver of Lost Cousins recommends putting all surnames into the search function. I found people descended from a Ringert Jongewaard and expanded their trees to meet mine. They are shared matches to each other. Ancestry won't list them as common ancestors as they are too far back. I was interested that such distant matches had reasonable amounts of cMs.
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With the new match function we can now add our relationship to known matches ...will that create new common leaf tagged ancestors
Out of interest
what dates are your common ancestors with more than one link ?
My mother has 4 DNA links to Nimrod GARDNER. 1756 of BUGBROOK Northamptonshire and his wife Susannah RODDIS 1756
& a few
5th cousins thru Richard Mawslbury1744(some don't show up because of spelling variations) but show thru his wife Hannah Higginson of Moreton Pinkney Northamptonshire 1751
Trees have been well researched !
The links go back further when descendency is thru younger children of younger children thru the generations .or children of older parents who can be a generation younger in years than their siblings but same generation in genealogy terms.
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With the new match function we can now add our relationship to known matches ...will that create new common leaf tagged ancestors
Out of interest
what dates are your common ancestors with more than one link ?
My mother has 4 DNA links to Nimrod GARDNER. 1756 of BUGBROOK Northamptonshire and his wife Susannah RODDIS 1756
& a few
5th cousins thru Richard Mawslbury1744(some don't show up because of spelling variations) but show thru his wife Hannah Higginson of Moreton Pinkney Northamptonshire 1751
Trees have been well researched !
The links go back further when descendency is thru younger children of younger children thru the generations .or children of older parents who can be a generation younger in years than their siblings but same generation in genealogy terms.
I've got a 20CM match and our closest known common ancestors seem to be born in the 1640s. We both descend from the same couple in two different lines which may explain how such a distant connection is possible.
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Wow thats very impressive history lives
Mums 5th cousin matches are 6-18cm
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Albu i suppose that is quite dangerous if the first cousins then went on to marry their first cousins from those 5 unions
But if they developed any family health issues how would you know if consanguinity or life conditions had affected them .
Not as bad as Egyptian royalty marrying their siblings !
Around 60 years ago in Lincolnshire there was a case widely reported at the time of two sets of identical twins who were also first cousins marrying. The mind boggles in any of their children followed suit and married their cousin. The consequences could be like those of Egyptian pharoahs.
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I have found a number of common ancestors, using BMD records and Census records, which Ancestry haven't found.
When i looked at some Public members trees, it is clear that Ancestry do not use all the information that they have in their system.
Gordon
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I've got 10 6th cousins showing via Common Ancestors, all of which appear to be correct. The connections go back to the early 18th century. I've also one match who is a 7th cousin which it doesn't pick up
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Thanks.
I have much the samr sort of results.
Gordon