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General => Ancestral Family Tree DNA Testing => Topic started by: JohnClogg on Tuesday 27 May 25 08:33 BST (UK)
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I am trying to understand why someone's Ancestry DNA profile is showing as no match on Ancestry but yet shows 60cM on MyHeritage?
We have both done Ancestry DNA tests, linked them, and then imported the DNA profile into MyHeritage.
Can anyone please help explain this?
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MH is well known for false matches up to 50cM and to a lesser extent at higher amounts.
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My partner was 40% Scandinavian on MH & 0 % on Ancestry. MH was a total waste of time & money.
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I won't have anything to do with MyHeritage.
Hundreds of bogus matches,
and where they duplicate Ancestry matches they ascribe too many centimorgans.
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John,
Hi, to answer your question. MyHeritage is technically correct. You are a 60 cM match.
The reason for the difference is the Ancestry Timber Algorithm.
https://support.ancestry.com/s/article/How-Timber-Helps-You-Find-Meaningful-DNA-Matches?language=en_US
As described this does some filtering, so that it is easier to find closer relatives. However, I am pretty convinced that it actually filters real matches.
I think this can be seen by the fact that using Ancestry Pro Tools, where someone has no shared matches without, suddenly you see lots when you use Pro Tools.
Ancestry has been shielding us from the complexity of DNA, if you go back 5 or 6 generations, most of us are from places where everyone was at leat distantly related to everyone else.
I have matches I can see are real but are at the 7 to 10 generation or more level.
You can argue about the philosophy of this, but personally I would like to be able to turn Timber off, and see the full picture. Which is effectively what you have done by copying your match data to MyHeritage.
Timber is great for the early stages and closer matches, but it is a filter. People saying you get false matches without MyHeritage are viewing the information through that Timber filter, so personally I feel they are not actually false, just further in the past than perhaps most people are interested in.
Personally I am interested in the fact that I can be pretty much certain of the fact that my ancestors came from sound Lincolnshire and the North East of Scotland. That is what all that extra data without Timber is telling me.
I hope this was not too mutch of a tome or rant!
As an update, this is quite informative also.
https://dna-explained.com/2022/05/12/ancestry-only-shows-shared-matches-of-20-cm-and-greater-what-that-means-why-it-matters/
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As noted above re. Timber. The amounts below about 100cM on MyH are about 40% higher on average than you'd get on Ancestry.
So 60cM = more like 36cM. On MyH that's probably between about 60-70% likely to be a false positive.
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There is no way to predict or calculate the difference as the two sites use different SNP's and also different sections of the chromosomes. MH use more SNP's but include segments within and adjacent to known pile up regions that Ancestry avoid.
I can have matches within 2cM of each other and others that are 2 or even 3 times higher on MH but on Ancestry are higher than the range Timber is applied to.
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I know. I use the multiplication by 0.6, as that is the mean difference between the two sites. It's more useful to have that figure than the MyH figure, since it's closer to the "real" IBD figure.
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Hi, yes it is complicated by other factors, but the John specifically asked about two sets of data downloaded from ancestry and uploaded to MyHeritage, so difference in testing does not apply.
By the way John, a belated welcome to RootsChat
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Hi,
A couple of further points.
Yes heritage matching is a game, based on the companies database.
Hence the recent change in the Ancestry database results.
I have gone from about 60% Scot’s to 60% Germanic, both correct, but from a genealogical point of view the revisal is pointless. It is simply saying that a vast percentage of the population of the UK came from the continent in the last 3 thousand or so years, so we share a lot of DNA.
The Timber algorithm does not have a specific cM cutoff, it is simply that if you have a match who shares multiple short matches, this is likely to be a more distant relative.
The white paper shows that for the Timber algorithm, they have made assumptions that may be true in the USA, though not for longer established families. Which is that people are unlikely to be doubly related.
This is I would say wrong in Europe, before the Industrial Revolution people did move but generally populations were much more stable. So people were much more likely to be doubly related.
The Timber algorithm means that they deliberately throw away match data, (partly at least on financial grounds), which are matches at the 7th to 8th generation level.
This means that you may miss that critical match to the family who know more about their ancestry, and take you back to 1700 or beyond.
In the USA it means that long established families may not be able to match their DNA in Europe, similarly hamstringing research.
See the Ancestry white paper on matching for the detail.
https://www.ancestrycdn.com/support/us/2025/01/2025matchingwhitepaper.pdf
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I am trying to understand why someone's Ancestry DNA profile is showing as no match on Ancestry but yet shows 60cM on MyHeritage?
We have both done Ancestry DNA tests, linked them, and then imported the DNA profile into MyHeritage.
Can anyone please help explain this?
I'm not sure there is a simple explanation for this, neither Ancestry's Timber nor MyHeritage imputation would account for it as, as has been said, both sets of data originated on Ancestry and were imported to MyHeritage.
I would start by getting a third opinion, GedMatch would be best as it gives you more control over the matching parameters, but FamilyTreeDNA would also work.
You actually have a really good opportunity to examine the differences between Ancestry and MyHeritage matching but it would involve a fair bit of work.
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I assume, and John may correct me, that the 60cM match is made up of several low cM segments in which case Timber is very much in play.
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Hi I did not expect to find so many people withe the same problem.
Some time ago I uploaded my DNA from Ancestry to My Heritage.
Recently MH have matched me with two first cousins once removed (different families)
I have checked out both families and found nothing in common.
They don't know me nor I them. I contacted the sister of one who was on Ancestry who was not a match to me.
Has anyone been matched so close?
Andrew
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Hi,
I have had a not dissimilar situation, but I was fortunate in the person in questions father had also tested. From that I could see that the child had matches from both father and mother, he had about twice the cM match to me than his father. I was fortunately able to trace back and find the MRCA on both sides. This was in fact around 1770.
More localised pedigree collapse can also make the MRCA seem much closer than it really is.
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Hi Andrew.
How much DNA (in cM) do you share with these new '1st cousins once removed' (1C1R) on MyHeritage? Usually, 1C1Rs share around 400 cM.
MyHeritage does sometimes seem to inflate the amount of shared cM - but that tends to be for distant matches (e.g. 45 cM instead of 22 cM; 60 cM instead of 35 cM; 35 cM instead of 20 cM).
If MyHeritage says you share 350 cM or 400 cM or 450 cM with a match, then that's probably going to be pretty accurate.
Do these new 1C1R match each other? Does the one with the sister on Ancestry match you on all the family lines that you should match? Does her sibling on MyHeritage match you on all the lines? Does the Ancestry person (A1) match you with people who are on MyHeritage? Do the new 1C1Rs on MyHeritage (MH1, MH2) match you with people who are on Ancestry?
Is your age similar to the ages of A1, MH1 and MH2? Do A1, MH1 and MH2 have ancestors from the same area as your ancestors? Have you been able to narrow down the family line on which you match A1, MH1 and MH2?
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I would start by getting a third opinion, GedMatch would be best as it gives you more control over the matching parameters, but FamilyTreeDNA would also work.
Gedmatch helpfully tells you where the data is imported from
I have looked at a few people who like me have imported from Ancestry.
Ancestry seems consistently a few cMs lower than Gedmatch
JR Ancestry 62 Gedmatch 67.6
GW Ancestry 37 Gedmatch 52.1 (unweighted on Ancestry 48, which is also longest segment)
MK Ancestry 32 Gedmatch 37
ID Ancestry 32 Gedmatch 36.3
GW was the surprising one until I checked the unweighted cM
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To. AnotherDay
Hi thank you for your interest. The following are hopefully the answers to your questions.
MH1 matches with me --- 344.6cM
MH2 matches with. --- 288.4 cM
MH1 does not match me even on the extended tree I have constructed for him.
His sister on Ancestry is not a match for me.
MH1 would appear to be about 20 years younger than me. His sister on Ancestry is 8 years younger than me.
I also “ share” 29 other matches with MH1. His niece matching 197.3 to me as second cousins daughter and 2017.3 with him. The remainder are 3rd to 5th cousins to both of us.
Yes MH1 has family connections to the area I was born. In fact he was born quite close.
Among the ten top matches four share the same family connections. Although two of them are siblings.
MH1 and MH2 do not share any matches. MH2 is rather more difficult due to lack of detail on the person involved.
If my MH1 and MH2 are related to me , it cannot be to the degree shown.
I have no maternal uncles and I think it safe to say all my known paternal uncles are accounted for. MH1 has a known father on his tree.
Andrew
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Hi,
Have you put these numbers into DNA painters shared cM Tool?
https://dnapainter.com/tools/sharedcmv4
It is quite informative.
You would seem to have one of two scenarios, or a mixture.
An NPE somewhere
An example of pedigree collapse.
From your description of shared matches at the 3rd to 5th cousin level, pedigree collapse seems the most likely.
The DNA painter site is suggesting that without pedigree collapse the ling could be 6 generations back. Have you got back that far?
Are there any known cases of cousins or second cousins marrying? These will both skew the numbers.
To understand this you are going to have to build as big a tree including as many of your matches as you can.
The What are the odds tool (WATO) may help you here.
Happy Hunting