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General => Ancestral Family Tree DNA Testing => Topic started by: Matriach on Saturday 28 January 23 22:44 GMT (UK)
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I understand that the ethnicity percentages given on Ancestry are within a range, but I do not fully understand their significance in relation to time. I thought I read somewhere that only the DNA from 5 or 6 generations back could be measured with any accuracy, but perhaps I imagined this.
From my paternal side I have inherited 10% Swedish DNA (it was 2% Norwegian and 8% Swedish). Only 2 close matches have more but that is I believe because we are related through both of my paternal grandmothers. Is this amount of DNA relevant to ancestors I could possibly find in church records? With one or two exceptions my paternal ancestors seem to have lived in Sussex or the Hants/Sussex border since the 17C.
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Average estimate seems to be 5 to 8 generations but it probably varies.
https://www.genealogyexplained.com/how-many-generations-does-dna-go-back/
Don’t take too much notice of ethnicity percentages. At best they are a rough guide. You could drive yourself mad looking for your 10% Swedish, and those percentages are going to change over time as more people take DNA tests. :)
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This might put it into perspective - Ancestry’s regions and number of people in the reference panels:
https://support.ancestry.com/s/article/AncestryDNA-Reference-Panel?language=en_US
As you can see, the numbers are not large in many cases, and regions are very general (and broad) in some examples, so not surprising some ethicities are lumped in with others. It’s more of a “best guess” really.
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Let’s get real with the Ethnicity Estimate.
Does is serve any useful purpose in terms of our Family History?
Does it loosen the bricks in that Wall?
Does it answer who my Great Great Grandfather was?
Does it tell me who I am?
Is it reliable?
No, to all then!
Is it a bit of fun, yes.
Do also remember, since our DNA year dot, our physical Ethnicity has not changed what has changed and changed out of all representation has been what Ancestry displays.
Now the rub, has Ancestry sold a shedload of DNA tests to people who are only interested in what it displays as their Ethnicity, undoubtedly.
Is it a very successful marketing ploy?
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Hi
Thanks for the replies to my post. I think I'll forget about those Scandinavians and continue with the evidence I find in actual church records (among others). I agree about the frustration of having a close match that has no family tree but wants only to prove their ethnicity - it can be fun though, as when my half Scottish daughter found that she had a Maori second cousin (i.e first cousin to her father). Messaging has shown how that came about......
Matriach
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You are confusing two different DNA scenarios. Matching with descendants of common ancestors is accurate and indisputable above match lengths of about 16-20 cM. With match lengths less than that, the chances that the purported match is false increase significantly the lower the match length, so that at 6 cM (which is the lowest match length that most DNA testing companies will report) there may be around a 50% likelihood that the proposed match isn't a genuine match at all.
The reasons for that are complex and varied, but because match lengths to ancestors decrease with successive generations, and therefore the generational distance between current relatives, it is generally accepted that a genuine match can only be determined over 5 to 8 generations at an absolute maximum.
But ethnicity estimates are a different (pseudo) science. They do not attempt to match you with relatives who have descended from a common ancestor within the last 5 - 8 generations. Instead, the theory is that segments of your DNA are compared to segments which the testing companies believe may be commonly found in groups of people (whether more recently related or not) who originated from particular regions within the last several hundred to a few thousand years ago.
As previous replies have said, the definitions of particular regions differ between different testing companies. The reference populations that are used to determine those regions are incredibly small in comparison to the actual populations of those regions - often only a few hundred people and in some cases fewer than ten. Ethnicity estimations to continental level are considered to be more reliable than those to individual country level or even regions within countries, and again, lower percentages allocated to particular regions are likely to be more suspect, so a supposition that you have 45% English ethnicity is quite likely to have some bearing of truth, whereas an indication that you inherited 2% Swedish ethnicity may well be totally incorrect.
So the assertion by one testing company that my ethnicity (as determined from my transferred to them Ancestry DNA test) is 98% European is, I think, quite likely to be reasonably accurate, but is it at all useful? Most people could probably give me an estimate with a similar degree of accuracy just by looking at me ;)
Whether you choose to believe and place any reliance on your ethnicity estimates is your choice. There may be a degree of expectation bias involved in people who claim that they are accurate. Personally, as already said, I choose to treat them as an informative but not necessarily accurate ploy to sell DNA tests to people who would otherwise have no interest in testing and the hard work involved in researching and identifying relatives descended from common ancestors.
I prefer to concentrate on using DNA matches with other people to further (and confirm or disprove) my research into my own ancestral lineage.
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Posted in error.
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Thank you, Biggles and Phil.
I wish you could get the message across to a few more people!
Judging by the number of unexplained matches, I'm wondering what use a DNA test is at all.
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DNA ethnicity estimates can be unreliable for a number of reasons. One reason is that the reference populations used to determine ethnicity estimates may not accurately reflect the genetic diversity of a particular population or region. Additionally, many commercial DNA testing companies use algorithms that are not based on rigorous scientific research and may not take into account the complexities of genetic ancestry. Furthermore, the geographic regions used to define ethnicity in DNA testing are often arbitrary and may not align with the cultural, historical, or political boundaries of a particular group. As a result, many DNA ethnicity estimates may not accurately reflect an individual's true genetic ancestry.
Mrs Zaph
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Thank you, Biggles and Phil.
I wish you could get the message across to a few more people!
Judging by the number of unexplained matches, I'm wondering what use a DNA test is at all.
A DNA is very useful, equally it can be very frustrating.
The big But is that despite having all the paper trails and citations the only way to know for sure that your tree is correct is via DNA linking you to DNA matches via a Common Ancestor(s).
Like Phil I do not specifically trust low cM matches but I have linked 22 DNA matches of 10cM and below to my Wife’s tree and another 43 in the 19-20cM range, so it can be done.
Conversely I have a 364cM match and a tree of 600 that I have built around them and no idea where the NPE occurred.
I had a new DNA match last year that leaded to me finding my Great Great Grandfather.
So DNA works.
Ethnicity less so, mine is very, very different to what it was five years ago. I mean very different, ie from 90% British to 37%.
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If I've understood what you're saying, Biggles, you were lucky.
I set my cut-off point rather higher at 27 cM, which is what one would expect for degree 8 (e.g. third cousins once removed), though the number can easily be twice as much or only half as much as theory would suggest: genes are not as predictable as some people think.
At Ancestry I have about 100 matches down to that level, and probably about the same at GEDmatch (I deleted my file there, so can't check just now), with some overlap, of course. Of those, I immediately recognized half a dozen cousins, and have since got the number up to probably 25, from people's replies (when they bothered to reply) or judging by shared matches. My family tree, compiled over the course of half a century and to some extent based on information from family bibles or handed down by great-uncles and other relatives in earlier generations, has about 3000 individuals. I reckon to know who almost all my 3rd cousins are.
That leaves a lot of unexplained matches. Possible reasons:
1. My great-grandfather and his brother were sowing their wild oats in Canada and Australia, or there was a 'leak' from another family somewhere. I think we're unlikely to find out, without being able to talk to the dead.
2. My sample of saliva was somehow contaminated. I've lived in this house for a dozen years. Is it possible that there's still DNA from the previous occupants, or from the next-door houses, floating about in the air? Or are the standards of cleanliness in the analysis lab not what they should be?
3. The whole thing is unreliable and doesn't mean a lot. After all, we share almost all our DNA with every other member of the human race, and a great deal with the apes. How do we know that the labs really are looking at the segments that do vary from person to person?
It certainly hasn't helped with my family tree.
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Thanks for all this input folks. I don't think I put my original question very well. I understand the difference between actual DNA matches and the ethnicity that Ancestry believes I have - which alters from time to time as they attract more punters to their pool of "examples". I wondered if 10% was enough to warrant spending time on research - afterall I know to whom the 4-8% of Irish DNA on my maternal side refers. General opinion seems to indicate probably not. My biggest problem would be the amount of inbreeding amongst a small community.
As previously mentioned I find the best way to sort out good matches that are not to be found on your family tree is to contact the match (or their shared matches) and hopefully get further insight. It is frustrating if you do not get an answer which is why I always reply to messages and e-mails even if I cannot be very helpful.
Warm regards to you all, Matriach
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Hugh,
1. if you have matches in Canada and Australia presumably you’ve considered that one of your ancestors,or one of their siblings or their descendants moved to those countries some time in the past.
2. I don't think your saliva test could have been mixed up with previous occupants or your neighbours. No idea about your dirty lab theory, but if that is true wouldn’t more of us find the same anomalies?
3. The autosomal DNA tests that most of us take are said to only detect matches up to eight generations back, so we wouldn’t match to everyone in the world on an Ancestry dna test.
It could be that part of your paper trail is wrong or you have one or more NPEs.
I’m the first to admit that I’m not too good at finding where myself and my DNA marches connect, and find myself putting lots into the “too hard basket”. I am largely stuck on the same few unsolved highish mystery matches. There are several who I know where they connect to my tree precisely, and some more vaguely. Despite that, even I have found numerous very good DNA matches (without even trying too hard).
In fact, recently working out where myself and one fourth cousin connected led to some very nice unexpected family histories. :)
Am now awaiting the results of my Ancestry DNA test to see what that brings. ;D
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Another way forward Hugh.
If you have around 25 matches that you can place in your tree, look at the shared matches of those matches. You can start grouping the shared matches to a particular family line as you know they are a match between you and your known match. Using the colour coding on Ancestry helps with that. If you have more than one known match to a particular line, say your paternal grandmother's family, you should notice some shared matches cropping up between you and all or more than one known match on that line. Look at the the shared matches of those shared matches and do the same. You should be able to attribute quite a lot of your higher matches to specific family lines.
It doesn't tell you who they are, but it is a start. From there, if you don't immediately recognise any of them from your own tree, it is a matter of picking the highest matches first (as they should be the easiest to resolve) and investigating them.
I don't contact many of my Ancestry matches as a matter of course, only if I think we might be able to help each other. Often, I can work them out through detective work. If they have a public tree and it is obvious they are in England or Wales you can start researching their own tree using the GRO index, FreeBMD and related Ancestry and other searches. You can often obtain mother's maiden names from birth records on the GRO index, but I fand the advanced search on FindMyPast much easier to work with in that regard, and it often has mother's maiden names which don't appear in the GRO index.
That information allows you to search for the marriage of the parents, as you have the mother and father's surnames. You can also search (again easiest on the FindMyPast advanced searches) for their other children, by father's surname and maiden name of the mother. I initially run those searches 9 years after the marriage, with a plus or minus 10 year window. That catches any child that might have been born just before a marriage, and those born up to 19 years later. You are effectively attempting to recreate their tree in the same way that you researched your own, all the while looking for possible avenues where your trees might converge and exploring them as fully as possible.
If your own tree is wide and deep, with brothers and sisters of each of your ancestors, their marriages and their children, the children's marriages and their own children etc., brought forward to the present as far as possible, it shouldn't be too difficult to discover the connection to many of your closest matches.
Yes, it can be hard and time consuming work, but DNA doesn't hand anything to you on a plate. It tells you that you have a relationship within a likely timeframe, and you have to do the research to discover the connection.
Also, the wider and deeper your tree, the more Thrulines hints you should find. Of course, they aren't necessarily correct as they rely on other user's trees to suggest connections, but they are another aid to your research. The more matches you can identify, the more you will find start to fit into place, and the more shared matches you should be able to allocate to specific ancestral lines.
Don't get me wrong, I'm not advocating identifying the exact connection between you and every single match. I only tend to investigate the closer matches (by highest cM) and others that I think will help confirm or disprove my other research. But by doing that and as a result being able to allocate more shared matches to specific lines, you will discover the matches that you can't allocate, which can direct your further research into those areas.
I have tens of matches that I have been able to attribute to my maternal grandmother's line and beyond through sorting shared matches of matches for instance. I don't intend investigating the majority of them, as I don't "need" them to corroborate my research. I already have several confirmed matches on that line to evidence that. But by being able to allocate them I can remove them from the equation and identify other matches that I need to sort. And I can always come back to them if I discover a need to look further on that line.
Also, when looking at shared cM as a guide to which matches to prioritise, don't just go by the total cM. Prioritise those matches with larger segment lengths and fewer segments. A match of 60 cM over a single segment is likely to be easier to resolve than one of 60 cM over several smaller segments for instance.
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My Heritage’s “autocluster tool” might be useful for you.
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Thank you, Phil.
The unresolved matches tend to come in groups of shared matches,
but I don't think any of them share a match with a known cousin.
So that doesn't lead me anywhere. It will probably all remain a mystery.
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I understand that the ethnicity percentages given on Ancestry are within a range, but I do not fully understand their significance in relation to time. I thought I read somewhere that only the DNA from 5 or 6 generations back could be measured with any accuracy, but perhaps I imagined this.
From my paternal side I have inherited 10% Swedish DNA (it was 2% Norwegian and 8% Swedish). Only 2 close matches have more but that is I believe because we are related through both of my paternal grandmothers. Is this amount of DNA relevant to ancestors I could possibly find in church records? With one or two exceptions my paternal ancestors seem to have lived in Sussex or the Hants/Sussex border since the 17C.
Swedish and Norwegian DNA for Brits is really just a component of British ancestry that has been there for 1000+ years in most cases. But having Viking ancestors is a selling point, so Ancestry try to separate it from the 'Anglo-Saxon' DNA. From my own examination of many matches and looking at their ancestry it does appear those who have a lot of ancestry from heavily Viking settled areas get a higher Sweden or Norway %. But as to other ethnicities that people may find coming up, very small %s below 5%, it could be anything from a gt gt gt grandparent or someone back in the early 1700s.
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But as to other ethnicities that people may find coming up, very small %s below 5%, it could be anything from a gt gt gt grandparent or someone back in the early 1700s.
Or simply random noise with no factual basis, at very low percentages.