Author Topic: MyHeritage Chromosome Browser.  (Read 339 times)

Offline Althea7

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MyHeritage Chromosome Browser.
« on: Monday 04 October 21 19:38 BST (UK) »
So far I have written down about thirty DNA matches on MyHeritage who all share a similar block of DNA on Chromosome 1 on the MyHeritage Chromsome Browser.  I am sure I could go on and find fifty or more others, but I am wondering what could be behind this pattern?

The block is always around the node, roughly in the same place as my cousin on my father's side, who I share 861cM, of which 24.3cM is on Chromosome 1 between 1061 and 1468 (it is a much longer number, but the first four digits seem adequate to label it with, and simpler).

Another close family match shares with me 20.1cM on Chromosome 1 between 1097 and 1468.

I do have other close family on MyHeritage, but they don't share this bit of Chromosome 1.  Both these family members descend from the same brother of my father.

But I have many, many matches who also share this bit of Chromosome one, all between about 29 cM and 12cM, and all overlapping with each other, all around the node on Chromosome one.

There is even one person from Finland who I share 23.3cM on Chromosome one, between 1078 and 1472, and another person from Sweden who I share 14.5cM on Chromosome one, between 1129 and 1468.  Other matches are from the USA, Australia, New Zealand, and the UK.

Is this some kind of fluke or will it mean that we share common ancestors somewhere?

Offline chris_49

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Re: MyHeritage Chromosome Browser.
« Reply #1 on: Tuesday 05 October 21 14:41 BST (UK) »
Disclaimer: I'm no expert but nobody else has replied.

At first glance, I found it odd that any substantial section of genetic code could be shared with distant cousins but not with close ones. However this is just on one chromosome. The near cousins could have inherited the equivalent segment from their mother.

Generally speaking, you should have more DNA in common with these cousins than with these distant ones (and how distant are they?) If you haven't you need to consider whether your uncle was not the father of his children. This link: https://isogg.org/wiki/Cousin_statistics gives some idea of probabilities. It does appear that at the fifth/sixth cousin level, there is so little in common that these remote matches are a coincidence. Or there could be a connection via another ancestor that you don't know about.

Anyone with better knowledge please step in and CMIIR (Correct Me If I'm wRong)
 
Skelcey (Skelsey Skelcy Skeley Shelsey Kelcy Skelcher) - Warks, Yorks, Lancs <br />Hancox - Warks<br />Green - Warks<br />Draper - Warks<br />Lynes - Warks<br />Hudson - Warks<br />Morris - Denbs Mont Salop <br />Davies - Cheshire, North Wales<br />Fellowes - Cheshire, Denbighshire<br />Owens - Cheshire/North Wales<br />Hicks - Cornwall<br />Lloyd and Jones (Mont)<br />Rhys/Rees (Mont)

Offline aghadowey

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Re: MyHeritage Chromosome Browser.
« Reply #2 on: Tuesday 05 October 21 15:18 BST (UK) »
If I'm reading your post correctly, Althea7, my OH has the same thing. Let me introduce you to his chromosome #2 (paternal side)-
30 matches (could be lots more, these are only the ones I have on DNA Painter so far) sharing the same bit of #2. Only 2 are known relatives (they are siblings to each other), several are local people we either know of know of (they don't know of any connection either) & the rest we have no clue.

Then there is chromosome #17 (maternal side)- 35 matches and again 2 known relatives (they are siblings to each other) but we don't even recognise any of the other names.
Away sorting out DNA matches... I may be gone for some time many years!


Offline Althea7

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Re: MyHeritage Chromosome Browser.
« Reply #3 on: Tuesday 05 October 21 17:57 BST (UK) »
If I'm reading your post correctly, Althea7, my OH has the same thing. Let me introduce you to his chromosome #2 (paternal side)-
30 matches (could be lots more, these are only the ones I have on DNA Painter so far) sharing the same bit of #2. Only 2 are known relatives (they are siblings to each other), several are local people we either know of know of (they don't know of any connection either) & the rest we have no clue.

Then there is chromosome #17 (maternal side)- 35 matches and again 2 known relatives (they are siblings to each other) but we don't even recognise any of the other names.

That sounds exactly my situation with Chromosome 1.  The two close relatives who share this area of Chromosome 1 are my cousin and a once removed cousin, both descended from the same paternal uncle.  The other thirty (and probably a lot more) are completely unknown to me.

The cousin I share total 861.7cM on 28 segments, and 24.3cM on Chromosome 1 (1061 to 1468). The cousin once removed I share total 534.2cM on 22 segments, and 20.1cM on Chromosome 1 (1097 to 1468).

My other first cousin, from a different paternal uncle, I share plenty of total DNA, but nothing on Chromosome 1, and two other known fairly close relatives with a lot of shared DNA with my cousins and known ancestry, I share nothing on Chromosome 1.

There are two other matches with quite a lot of shared DNA, that match my cousins, and I am fairly sure which common ancestors we share, who I don't share this area on Chromosome 1 with either.  So maybe I could interpret this to mean that the common ancestor I am looking for on Chromosome 1 is not on the same ancestral line as these people?

Offline aghadowey

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Re: MyHeritage Chromosome Browser.
« Reply #4 on: Tuesday 05 October 21 20:21 BST (UK) »
Not sure it's that straight-forward. Taking DNA results (not just one particular chromosome), I have match (through my paternal grandfather) to two siblings I'll call A & B. Their 1st cousin (C) is also from this part of the family but doesn't appear as a match to me. Now, OH also connected to this family (although he & I are not related by blood) but he matches A & C but not B.
Away sorting out DNA matches... I may be gone for some time many years!

Offline Althea7

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Re: MyHeritage Chromosome Browser.
« Reply #5 on: Wednesday 06 October 21 00:58 BST (UK) »
Not sure it's that straight-forward. Taking DNA results (not just one particular chromosome), I have match (through my paternal grandfather) to two siblings I'll call A & B. Their 1st cousin (C) is also from this part of the family but doesn't appear as a match to me. Now, OH also connected to this family (although he & I are not related by blood) but he matches A & C but not B.

That is weird.  I suspect there are a few wormholes in the DNA matching system.  I also find it weird what I just described, and not sure what to make of it, all the matches, probably in the end getting on for a hundred of them,  seem to have between about 12cM and 29cM just on Chromosome 1, across its node, all overlapping each other, and only two of these matches are close relatives.

Offline Althea7

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Re: MyHeritage Chromosome Browser.
« Reply #6 on: Wednesday 06 October 21 03:45 BST (UK) »
Having noticed that some of these matches are from Sweden, I now went straight to the area of MyHeritage where Swedish matches are listed, and though I haven't had time to go through all of them on this list, loads of them share this same area on Chromosome 1.

I do know that on my father's side my family have a lot of Scandinavian DNA, we all have a high percentage of Scandinavian DNA, and blonde hair, blue eyes and fair skin, and beyond that I have noticed these traits in people from the Midlands area around Birmingham.  I am wondering if it relates to people in my family tree who came from the Leicestershire/Northamptonshire border area for many centuries before moving to Birmingham in the nineteenth century.

The shared DNA is a significant amount, well above the 8cM considered to be significant, but I don't think it relates to common ancestors in the past five generations, I think it is older than that.


Offline melba_schmelba

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Re: MyHeritage Chromosome Browser.
« Reply #7 on: Wednesday 06 October 21 12:01 BST (UK) »
Having noticed that some of these matches are from Sweden, I now went straight to the area of MyHeritage where Swedish matches are listed, and though I haven't had time to go through all of them on this list, loads of them share this same area on Chromosome 1.

I do know that on my father's side my family have a lot of Scandinavian DNA, we all have a high percentage of Scandinavian DNA, and blonde hair, blue eyes and fair skin, and beyond that I have noticed these traits in people from the Midlands area around Birmingham.  I am wondering if it relates to people in my family tree who came from the Leicestershire/Northamptonshire border area for many centuries before moving to Birmingham in the nineteenth century.

The shared DNA is a significant amount, well above the 8cM considered to be significant, but I don't think it relates to common ancestors in the past five generations, I think it is older than that.
There is something a bit iffy about MyHeritage's matching system, but it may be partly due to inaccurate imputation from matching uploads from other companies (i.e. which often means other chips which look at different areas of the DNA). This user compared their own matches from a LivingDNA upload on MyHeritage to the matches of their parents' LivingDNA uploads and discovered that 1/3 of the matches with segments under 17.6cM were false

https://anthrogenica.com/showthread.php?22577-British-and-Irish-Folks-Who-are-your-closest-continental-European-matches&p=773815&viewfull=1#post773815

They also think you can get some IBS matches (rather than IBD Identical By Descent) up to 26cM segment size.

Offline Zaphod99

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Re: MyHeritage Chromosome Browser.
« Reply #8 on: Wednesday 06 October 21 12:28 BST (UK) »
Research 'pile-up regions'.  Certain well-known segments are known to exhibit this phenomenon, but also, individuals can also have their own addition ones.  I find it very difficult to know whether I have found many distant relatives, or a personal pile up area.  Start here,

https://www.wikitree.com/g2g/572809/is-this-a-known-dna-pile-up-area

Zaph