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General => Ancestral Family Tree DNA Testing => Topic started by: Lubricated on Wednesday 02 April 25 11:10 BST (UK)
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Sorry, need a rant!
I regularly look at Ancestry Trees to help my research but I ALWAYS, without fail, check the information therein. Haven’t kept statistics but I would say a significant majority of these trees are poor quality (polite euphemism).
In the latest example, I have an ancestor who was (according to almost every one of 40+ trees!) allegedly born in Middlesex in the 1780s and then taken a few days later to Wiltshire in order to be baptised. She allegedly then survived until after 1851; in the 1841 Census she was enumerated in her married name but reverted to her maiden name for the 1851!
What worries me is that Thru Lines is based on these fairy tales.
I’m regularly being told I have a common ancestor with a DNA match where the match is on my paternal side but thru lines extends back to my maternal line. And vice-versa.
It’s worth noting that Thru Lines is an anagram for u lern this. This makes another anagram!
Rant over.
Lubricated.
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I think people are generally aware of the fact that Thru Lines data is based on other people's trees, but I've been very impressed with it. It's not perfect, but it has helped me no end. The one thing I'd point out though is have you considered that some of your tree might actually be connected to ancestors on your paternal and maternal side? I've got one or two like that.
Zaph
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I'd guess that maybe 1% of connections in Ancestry trees are incorrect, later than 1800, and more before that.
A big part of the issue is that Ancestry suggests people add more generations to their tree from others. So once one person makes an error, then it gets copied by people who don't know how to research properly.
Not long ago a cousin of my father popped up as a match. I sent him a lengthy file based on proper research. He promptly ignored it went about adding a bunch of Ancestry suggestions to his tree, including a number of casual and catastrophic errors.
When you meet such people in life you may hear things such as "Oh, I've researched the family tree." When in reality they've just copied "research" without question. Other common lines are, "We go back to the 12th century", ... William the conqueror or Charlemagne... Maybe. But the paper trial is more likely to be dubious.
I am very careful with making connections with DNA, because it's easy to make connections where there is no overlap with trees and DNA, if you don't know what you are doing.
The worst one I have found in my tree is an ancestor Janet Hamilton was born c 1793 in Ayrshire, Scotland. Her father is given as Alexander Hamilton, b. 1786 in New York City, who is in turn the son of Alexander Hamilton, 1st Secretary of the Treasury of the US. This has been copied into many trees. But on her death certificate, which costs about £1.50 to order, the parents are listed as something else.
It's also common to see many trees with mad scrabbles back though the 16th-18th centuries. Maybe there is a baptism in Cornwall, the line then goes to Maryland, US, then Lincolnshire, and before ending in South Wales.
I also find that US immigrant lines back to the UK tend to be incredibly unreliable.
But from the perspective of DNA the trees are immensely useful. If Ancestry didn't have this vast repository of often shaky trees, I would be missing a few lines I have solved with DNA. You just need to know the pitfalls and what is possible with paper and DNA trials.
Personally I don't even use Thru-lines. To be sure of the information you can extract from DNA matches, you need to go through all of them down to 20cM and more of the shared matches below 20cM. If you have ancestors in a concentrated area, clusters of matches can become jumbled due to overlapping on more than one line. For a long time I thought that one of my lines was via an NPE. But when I systematically went through all matches I found that I had two lines where almost all of the matches shared 2+ lines of ancestry.
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I don't stand by it 100%, but if people have got more than two or three thousand people in their tree, I really don't think they can be properly researched. I rarely bother looking at them.
I know some people will say they've got five thousand (or often many more) in their tree and it's all properly researched, which is why I said I don't stand by my first statement 100%. Most people seem to forget that even if one or two percent of births are not down to the known father, it makes a mockery of everything that happened earlier, and possibly later. Also, if people haven't been DNA tested I'm less likely to be enthusiastic about their tree.
Zaph
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Have I considered some of my tree might actually be connected to ancestors on both my paternal and maternal sides? Yes I have, though I have not yet found any. On the flip side, I have found 3 DNA matches who connect with me on both sides of my ancestry, the closest being a 3rd Cousin 1xremoved on my paternal side and 5th Cousin 1xRemoved on my maternal side.
I acknowledge that some of the thru lines have been very useful, but it is quite very tiring sorting the wheat from the chaff. I am very lucky; both my parents tested with ancestry so my first port of call is to check the predicted side of my ancestry. BUT this in turn brings up other anomalies; I have two DNA matches who are not matches to either of my parents! Am I the only researcher with three biological parents?!
There are nearly 6,500 persons in my tree. Every fact, including name and gender, is sourced. Nothing goes in unless I'm certain. It is now my practise as I go back each generation to try and find siblings and then develop the lines of those siblings forward towards the present day, in the hope this will identify more Common Ancestry connections amongst my DNA matches. The unidentified residue will then be the ones most likely to be able to help break down my brick walls.
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I have 175 Thrulines / Common Ancestor DNA matches.
Of those there are 147 who have been included in my tree.
So there are 28 Thrulines that are dubious.
Of those 28 there are 14 that I have assigned to the TLW Group (Thru Lines Wrong).
Typically Grandparents born and raised and died in the UK.
Son born and raised and died in the USA.
Grandchild born and raised and died in the UK.
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I would guess that 147 out of 175 is about the same proportion of good ones that I found, although I haven't been lucky enough to have that many.
In my tree of 2,000 members, I've identified 35 to 40 from DNA matches. Some were already in my tree, and some have been added as a result of research into my shared matches. While I'm here I will emphasize how important looking at shared matches can be. It can really help you cluster some of them into small groups of interrelated people.
Zaph
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I have a cousin who is green as grass with family history, they did a test and within days had a tree of 1,000 names. It takes a wrong turn four generations in but so do dozens of others.
I can't blame Ancestry or Thrulines for the way she misuses them or for ignoring her dna results.
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I like to distinguish Thru Lines from Common Ancestors although I suppose they're really the same thing.
Thru Lines I take to mean the suggestion of parents for my Tree Tops, these are 100% useless for me.
Common Ancestors being the connection from a point on my tree to a DNA match. These I find very useful being able to make connections via one or more (possibly private) third party trees which I would never have found. These have given me hundreds of connections and although not 100% is very useful.
What I really want is a way to reject a suggestion so that Ancestry will suggest a different connection. I can block the Thru Lines by creating an unknown parent but what I want is further suggestions.
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I have just upgraded the tree linked to my father’s DNA test on Ancestry. When I called up his DNA matches, I was presented with the top 20 of All his matches, with an option above them to view “By parent”.
When I selected “By parent” I was presented with a screen with the following:
“Which side of the family are your ancestors on? We can now show you – even without testing your parents”
That is some claim! Gives the impression of being right on the forefront of this developing science!
So why then does Ancestry tell me a match is on my paternal side accompanied by a thru line to my maternal side? Or vice versa? Does not happen all the time but it happens often enough to undermine their credibility. Leaves me wondering - which bit is right?
I acknowledge without question that Ancestry is not responsible for what people put in their trees, but if they have the scientific capability to be able to tell me that a match is on my paternal side, it shouldn’t take too much programming effort to make sure any accompanying through line is also on my paternal side. And restore their credibility.
When looking at any on-line tree, including mine, the viewer should always remember GIGO!
Lubricated
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I agree and have wondered myself why such clever algorithms sometimes crash into ones that are seemingly very weak. I also wonder why Thrulines sometimes seems to ignore my own linked tree and plops for a situation which is patently not the case.
That said, I think ThruLines are extremely useful as long as you know what they are and where they come from
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So why then does Ancestry tell me a match is on my paternal side accompanied by a thru line to my maternal side? Or vice versa? Does not happen all the time but it happens often enough to undermine their credibility. Leaves me wondering - which bit is right?
They say their ancestral line labels are about 90-95% accurate, which I would say is about right. With much of the inaccuracy coming from lower cM matches.
The common ancestor matches are suggestions. They could limit them to when they only match the judged relevant sides of ancestry for both parties. But then they may not show them when their ancestral line predictions are wrong. Some people don't define the sides of Ancestry, probably about 50%, so that complicates things. And you can guarantee a minority have assigned the wrong side. It would be useful if Ancestry also told you the side of the match's ancestry they think it relevant.
I think that Ancestry only shows one common line of possible shared ancestry. While there are sometimes two or more. So they could perhaps show more than just one.
As with member trees containing a lot of errors and shared matches - the suggested common ancestors are a point of reference, which need to be looked into further.
It's much better they provide these tools and people make what they can of them, rather than not providing them at all. Just as most people don't know how to research using paper records and generate invented lines, people misuse the information provided via DNA matches out of not knowing the limits and pitfalls...
I've seen some people who have used DNA to construct invented lines. As one example, one group of my matches has a birth out of wedlock and one descendant has word of mouth information that the unknown ancestor was a Baron Leigh. They say they have found evidence of this in their DNA matches, but when I looked through their matches found it was a few wisps of a couple of the Baron Leigh's ancestral surnames in the 1600s. Another match has used DNA to fill in a dead end, where he found a single Patrickson match to his Patrickson dead-end and added the earliest possible ancestor from his match as his ancestor. My grandmother was born out of wedlock and Ancestry DNA suggested the entire line of her mother's later husband's ancestry as thru-lines. This owing to all ancestors living in a small area. So of my matches, various of them just happened to have ancestors that suggested this was my ancestry. But none of those matches with this suggested ancestry overlapped with DNA...
If you want to extract useful information from Ancestry DNA, it involves going through all the matches manually, considering how each overlaps with others, extending trees beyond what matches have listed themselves. The suggestions of paternal-maternal lines, cM levels, shared matches are clues which need to be deciphered. They could and should (for the price they charge for ProTools) provide more and better tools in this endeavor, but they still have the best system overall by a long way.
In the case of common ancestors, when you add a person to a tree on Ancestry, they check to see if they think that person has been entered in [an] other tree(s). Each person is assigned a unique identifier. The way they locate your thru-lines is by plugging your tree into their amalgam of all trees. Thus the suggestions rely on what users have submitted. There is no checking if what they have submitted is correct, as it would be infeasible.
There's a lot of stuff you need to know when working with DNA and then a lot of work to figure out how matches relate to you. What Ancestry can do by itself are useful time-saving suggestions, which may be wrong. As a few small extras I've found:
1) Sometimes there is no linked tree, but it you click through to the match's profile there can be public trees; or sometimes bios that are enough to piece together a tree yourself
2) Sometimes there is a linked tree, but it appears it has only one person in it, but above it says something like "tree with 1,456 people", if you click through to that, you often find a link somewhere in the tree
3) It's not uncommon to find linked trees when the wrong person has been linked, usually the spouse of the person who took the test; and that can sometimes be fairly obvious by comparing the ethnicity estimate, e.g. the linked person is half Italian, half British, while the ethnicity of the test states half Polish, half British; and that can fit the spouse of the linked person