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Molfish
07-23-2018, 07:32 PM
I get a DNA match from Norway at 34.9 cM, or the equivalent of 0.5% shared DNA. A not insignificant amount I think.

I have no known non-British Isles ancestry, so how likely is this to denote a genuine recent common ancestor? Is it common on MyHeritage for British/Irish people to get Scandinavian matches at this level?

There was a chart for this but I can't seem to find it.

msmarjoribanks
07-23-2018, 07:50 PM
The match might have some more recent British/Irish ancestry. Have you checked on that?

Also, 34.9 cM with how many segments? What's the longest segment? Those can make a difference.

Here's a chart: https://dna-explained.com/2017/09/21/shared-cm-project-2017-update-combined-chart/

Molfish
07-23-2018, 07:59 PM
The match might have some more recent British/Irish ancestry. Have you checked on that?

Also, 34.9 cM with how many segments? What's the longest segment? Those can make a difference.

Here's a chart: https://dna-explained.com/2017/09/21/shared-cm-project-2017-update-combined-chart/
Thanks.

3 segments, the largest is 21.2 cM.

All their Grandparents surnames are Norwegian, and on the public side of their tree going back to the Mid 19th century, so I'd say recent British/Irish ancestry is unlikely.

PoxVoldius
07-23-2018, 08:23 PM
For reference, on MyHeritage I have a DNA match in Germany that I can confidently place in my family tree. We share 39 cM across 2 segments; largest segment is 19.8 cM. The most recent common ancestors between us are one of my 4th-great-grandfathers, who was born in Poland in 1817, and his wife who was born in 1823 also in Poland.

Molfish
07-23-2018, 08:30 PM
For reference, on MyHeritage I have a DNA match in Germany that I can confidently place in my family tree. We share 39 cM across 2 segments; largest segment is 19.8 cM. The most recent common ancestors between us is one of my 4th-great-grandfathers, who was born in Poland in 1817, and his wife who was born in 1823 also in Poland.
The thing is, it's hard to imagine a Norwegian ending up in the places my family is from in those days (even more so vice versa), but I guess it's possible.

Ais
07-23-2018, 08:30 PM
How far back have you gotten in your tree? I have a similar issue, I have several matches of around 35cM with people it makes little sense for me to match with, and I think it either comes from my mystery line on my mother's side, or is very old, as I can't find anywhere our trees intersect (and they have well researched trees back to the 1600s).

On the other side of that, I have quite close family matches that I share almost no DNA with. Just today I found someone I only share 7.6cM over 2 segments with, and she's a 3rd cousin!

msmarjoribanks
07-23-2018, 08:37 PM
It varies a lot. I have a few matches of over 50 cM with the longest in the 20s for people where the MRCA is back in the 1700s, but in those cases there's reason to think there might have been some degree of cousin marriage (non-conformists in England, people in rural areas in the US who seemed to travel as a group of families).

Any common matches or ability to tell what side of the family it's on?

Molfish
07-23-2018, 08:49 PM
How far back have you gotten in your tree? I have a similar issue, I have several matches of around 35cM with people it makes little sense for me to match with, and I think it either comes from my mystery line on my mother's side, or is very old, as I can't find anywhere our trees intersect (and they have well researched trees back to the 1600s).

On the other side of that, I have quite close family matches that I share almost no DNA with. Just today I found someone I only share 7.6cM over 2 segments with, and she's a 3rd cousin!
I have 15/16 surnames for Great x2 Grandparents, and 21/32 surnames for Great x3 Grandparents, so a lot of holes, but no trace of any foreign names, nor would I really expect any in those backwaters. Do you have any continental matches that high?

Molfish
07-23-2018, 08:59 PM
It varies a lot. I have a few matches of over 50 cM with the longest in the 20s for people where the MRCA is back in the 1700s, but in those cases there's reason to think there might have been some degree of cousin marriage (non-conformists in England, people in rural areas in the US who seemed to travel as a group of families).

Any common matches or ability to tell what side of the family it's on?
They're not a match for my Mother. My father's side of the tree is significantly less filled in, the records in Ireland are not great.

Ais
07-23-2018, 09:18 PM
I have 15/16 surnames for Great x2 Grandparents, and 21/32 surnames for Great x3 Grandparents, so a lot of holes, but no trace of any foreign names, nor would I really expect any in those backwaters. Do you have any continental matches that high?

Nothing that high, my highest continental matches tend to be between 10-20cM, with the largest single segments around 15cM, although most of them are smaller than that. The 35cM matches I mentioned are people of Colonial American ancestry, whose families moved over in the 1600s.

timberwolf
07-23-2018, 09:31 PM
I would take anything from Myheritage with caution. I have had medium confidence matches with people from Germany, Netherlands and Norway and now I have Belgians and French turning up.

Perhaps try contracting them, to find out if they have British ancestry might be the first step, or look at their matches? Having any of them actually reply to your message, might be the tricky part.

Pylsteen
07-23-2018, 09:41 PM
I would check the chromosome location of the matching segments. There are some locations that can not be used well since everyone tends to clutter together such as the beginning of chrom 15 etc.

timberwolf
07-23-2018, 09:57 PM
I would check the chromosome location of the matching segments. There are some locations that can not be used well since everyone tends to clutter together such as the beginning of chrom 15 etc.

What are some other pile up regions?

Ais
07-23-2018, 10:05 PM
What are some other pile up regions?

This page is good at laying out the main pileup areas http://www.khazaria.com/genetics/excess-ibd-regions.html.

It's not an exhaustive list though, some people have pileup regions that aren't generally considered to be such. For example, I have an area in chromosome 7 in which I get lots of Norwegian matches, but there are oddities in the cM and SNPs, and in the triangulation, that make me fairly sure they're not genuine. Or if they are, they are very old.

timberwolf
07-23-2018, 10:16 PM
This page is good at laying out the main pileup areas http://www.khazaria.com/genetics/excess-ibd-regions.html.

It's not an exhaustive list though, some people have pileup regions that aren't generally considered to be such. For example, I have an area in chromosome 7 in which I get lots of Norwegian matches, but there are oddities in the cM and SNPs, and in the triangulation, that make me fairly sure they're not genuine. Or if they are, they are very old.

Thanks, that is exactly what I was looking for. I am certainly of the opinion that most of my non Brit matches are false.

Still I was able to triangulate some matches of chromosome six, with some people of Iberian descent. which was the part of Ch6 that 23andme identified as Iberian.

Maybe more to that? Then the obvious false matches.

Molfish
07-23-2018, 10:25 PM
I would check the chromosome location of the matching segments. There are some locations that can not be used well since everyone tends to clutter together such as the beginning of chrom 15 etc.
My largest segment is on 15 (21.2 cM). The other two are on 16 (6.6) and 17 (7.1).

I wish I knew the significance of any of that.

msmarjoribanks
07-23-2018, 11:02 PM
You could see how many other matches you have on those areas in Gedmatch (which lets you do that). That should tip you off to whether they seem like pile-ups and also to other matches who would likely be common ones.

RobinBMc
07-24-2018, 01:25 AM
The thing is, it's hard to imagine a Norwegian ending up in the places my family is from in those days (even more so vice versa), but I guess it's possible.

It's also possible some distant cousin of yours went to Norway.

https://dnapainter.com/tools/sharedcmv4/35

But I do think MyHeritage still has some issues with matching. When they first started with it, I had a ridiculous high amount of either false positives for myself or false negatives for my parents. They made some changes and it's not as bad now, but I think there's still some reports of it. So I would not dismiss the possibility that this person could just be a false positive for you. Do you have any Shared DNA Matches and if so, what are their origins?

msmarjoribanks
07-24-2018, 03:06 AM
My largest segment is on 15 (21.2 cM). The other two are on 16 (6.6) and 17 (7.1).

I wish I knew the significance of any of that.

So interesting -- I have a few Norwegian matches, so I picked my top one (29.8 cM, 3 shared regions), checked common matches (seemed to be very mixed, American, UK, Finnish, as well as Norwegian, person's ancestry was all Scandinavian and Finnish), and then checked to see if the matches seemed to be on pile up regions. They weren't, at least not noticeably. I then realized neither of my parents had come up as common matches, so I double checked and neither of them were matches.

I then clicked on a common match with an Anglo name (he was a tiny match with the Norwegian match, 20 cM with me), and my dad showed up as a match of his, but only 12 cM.

Based on this I'm thinking that maybe it's just that there's enough common ancient ancestry that you are getting matches that are taking some from one parent, some from the other, so they are false positives.

xenus
07-24-2018, 04:43 AM
A few points I can add. First is that even if there weren't a lot of families moving in or out of an area there were more chances for single men to end up migrating. Scenarios like going off to fight in a war or moving to a city where their descendants would have more mobility. All it would take is a single person assimilating and changing their name to erase surname clues or a "non paternity event" in either of your lines at any point.

False matches from naively analysed data are still really common but having multiple generations of dna results can help with that too

firemonkey
07-24-2018, 06:35 AM
I get 56 matches for Norway with My heritage. However quite a few of them are in a pile up region for Chr 10 44/45-53.

evon
07-24-2018, 09:18 AM
I get a DNA match from Norway at 34.9 cM, or the equivalent of 0.5% shared DNA. A not insignificant amount I think.

I have no known non-British Isles ancestry, so how likely is this to denote a genuine recent common ancestor? Is it common on MyHeritage for British/Irish people to get Scandinavian matches at this level?

There was a chart for this but I can't seem to find it.

Is it located on a pile-up? As Myheritage is notorious for listing pile-up matches on certain regions (usually around at 10-25cM), see here for more info on pile-up regions:
https://anthrogenica.com/showthread.php?13243-Pile-up-related-matches-at-commercial-DNA-companies-(23andme-Myheritage-FTDNA-)

Molfish
07-24-2018, 09:27 AM
It's also possible some distant cousin of yours went to Norway.

https://dnapainter.com/tools/sharedcmv4/35

But I do think MyHeritage still has some issues with matching. When they first started with it, I had a ridiculous high amount of either false positives for myself or false negatives for my parents. They made some changes and it's not as bad now, but I think there's still some reports of it. So I would not dismiss the possibility that this person could just be a false positive for you. Do you have any Shared DNA Matches and if so, what are their origins?
The only shared DNA matches are more distant than the Norwegian, certainly nobody I would recognise. One of them Swedish (20.3 cM), the rest American. None from the British Isles.


I get 56 matches for Norway with My heritage. However quite a few of them are in a pile up region for Chr 10 44/45-53.
Do you get any Norwegian matches in the 30 cM or above range?

The chart I was looking for was a percentage likelyhood of a match being real based on centimorgans. I think it was virtually 100% chance for 50+ cM, Mid 30s was a bit more iffy but still very likely.

firemonkey
07-24-2018, 12:07 PM
The only shared DNA matches are more distant than the Norwegian, certainly nobody I would recognise. One of them Swedish (20.3 cM), the rest American. None from the British Isles.


Do you get any Norwegian matches in the 30 cM or above range?

The chart I was looking for was a percentage likelyhood of a match being real based on centimorgans. I think it was virtually 100% chance for 50+ cM, Mid 30s was a bit more iffy but still very likely.


No such matches 30 cMs+.

geebee
07-24-2018, 04:25 PM
I just found a connection to someone from Spain. None of the shared segments is larger than 10 cM, but there are three segments shared. They are 7.4 cM, 7.7 cM, 9.6 cM.

I feel comfortable in sharing the one surname that we have in common -- Pons -- mainly because it's an extremely common surname in Menorca, which is where my 2nd great grandfather and his parents and siblings emigrated from in the prior to 1840. This is also where my match's ancestor was born, in 1866.

I should note that MyHeritage reports that we have no surnames in common, but that's because it apparently doesn't recognize that each part of a Spanish double surname is actually a separate name. Typically, Spanish surnames consist of the paternal surnames of both parents -- separated only by a space.

My 2nd great grandfather did something like that in America, except that he used "y" as a separator: "Pons y Olivas". I think that's how I have his name in my tree at MyHeritage, but I also show Pons by itself for my great grandfather and my grandmother.

If my match's great grandmother was born in 1866, it seems reasonable to estimate that her mother -- whose paternal surname would have been Pons -- was born between 1820 and 1835, give or take a few years.

Anyway, this very likely is a genuine match.