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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.