"Unmixed" ancestry - rarer than hen's teeth?

Question

All of the known ancestry of my paternal aunt was assumed be from the British Isles because of her ancestral surnames and given that they settled in the British colonies of Bermuda and the Bahamas.

http://www.wikitree.com/treewidget/Roberts-7123/5   

I tested her autosomal DNA with 23andMe soon after that test became available.  It revealed she was mostly Northern European, but a significant amount of her auDNA was most similar to Southern Europe and the Mediterranean region.

So what would the ethnic admixture look like for someone who could trace all their ancestral lines back 4 generations to only England? How would it compare with my aunt?  Only with WikiTree could I begin to figure how to do that.

I did not realize the rarity for each of following criteria.  1. Persons who can trace all their ancestral branches for 4 generations. 2. Those persons who can trace all those ancestral branches to the same country (of indigenous origin). 3. Those persons who also have a GEDmatch ID.

Here is the small handful of people I've been able to find:

http://www.wikitree.com/wiki/Space:Autosomal_DNA_Ethnic_Admixture_and_Ancestry

GEDmach's Eurogenes shows my paternal aunt as 42.94% North Atlantic, 21.59% Baltic, and 15.98% West Mediterranean.

One person in WikiTree with "100%" English ancestry is 49.08% North Atlantic, 23.49% Baltic, and 14.73% West Mediterranean.

Another person in WikiTree with "100%" English ancestry is 51.34% North Atlantic, 22.35% Baltic, and 13.58% West Mediterranean.

I'm still looking for a much larger sample population to compare with!  I did not think it would be so difficult to find people who trace all their ancestry to one country (and have been auDNA tested).

Comments

Those numbers are remarkably consistent.  Presumably they represent the make-up of England before genealogical time, and anybody who is "pure English" will have a similar set.

What this shows is the danger of thinking you must have a recent Spanish ancestor to account for your 15% West Mediterranean.  It could just as easily go back to the Roman Empire.

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That is my thinking also. Thanks.

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Except for the DNA test my father would probably have met your criteria (depending how you define 'country' as related to the Netherlands) - 5 generations of ancestors complete and all from the Netherlands, One 6th Generation ancestor is from 'over-the-border' (in Braunschweig-Lüneburg), and ten 6th Generation ancestors are either unknown or 'unknowable'.

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Yah, That would be me!!!

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Actually there's some circularity here because genes are labelled according to where they predominate.

So just the normal drift over time will tend to create a situation where the majority genes are those labelled as local, with an admixture of the genes associated with surrounding areas.

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This is the best explanation for why FTDNA labels me  98% European and 2% Middle Eastern, despite the fact that I know for certain that I do not have any Middle Eastern ancestors. But my YDNA R1a1a1b2 is labeled Eurasian, outside of my Surname DNA project it is not found in Britain or Western Europe, but it is found in some Turk and Arab populations

On the other hand 23andme has a completely different origins, they have me 100% European and then breaks it down into

96.9% Broadly Northwestern European

.7% Southern European

.3% Ashkenazi

3.1 Broadly European (whatever that is)

I know all 8 off my great grandparents, all but one of my 16 2nd great grandparents

I know the given names of all of my 2nd great grandparents as well as their places of birth and the surnames of 29 of the 32, 

It gets sketchier after my 2nd great grandparents, but based on the time, and where they lived I am pretty sure that there is no Mid Eastern ancestor.

J2b1a = Found in Western Europe and Russia https://en.wikipedia.org/wiki/Haplogroup_J_(mtDNA)

R-Z93 (R1a1a1b2)

This large subclade appears to encompass most of the R1a1a found in Asia. https://en.wikipedia.org/wiki/Haplogroup_R1a#R-Z93_.28R1a1a1b2.29

But I have no Asian ancestors, and to my knowledge no Ashkenazi ancestors either. Although I don't object to either.

 

 

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I trace all but one of my lines to the British Isles, that exception is my great grandmother whose parents, Weller, migrated from Prussia circa 1865. She was born 1866 and taught me her family history, as well as cussing and praying in German.

My fathers ancestry arrived in Virginia and the south in the 17th and 18th Century. My mothers ancestors, those that I know of, arrived in the 18th Century, save for the Prussians.

Fathers family,all ancestors, are English. Mothers Family mostly Scots Irish, save for her fathers, father, father line and then it is all English, best as I can determine.

Answer 1

England has been trading with the rest of the world for centuries. And don't forget the Vikings, the Romans, the Normans etc who crossed the channel and set up shop. In each case there have been those who stayed and raised families and those who left but left behind one or more descendants. And then there are the refugees who arrived in the British Isles from less salubrious regimes. All of this is ignoring the influx of people that started slowly after World War I and has steadily increased. When England was at the height of its powers and head of the British Commonwealth members of the Commonwealth were able to live and work in England to a certain extent.

The average Englishman or Englishwoman is a mixture. I'm a mixture myself and my ancestors are from England.

Comments

Thank you.  I understand the average person from England is a mixture.  "So what would the ethnic admixture look like for someone who could trace all their ancestral lines back 4 generations to only England?"

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An admixture is what I would guess unless they lived in a rural area that had little contact with anyone outside the county. Even so, the Romans were all over England (Hadrian's Wall is an example of that), and Normans were the ruling aristocracy and sent their people around the country to make sure the peace was kept.

My guess is that Wales may be more "Welsh" than the average Englishman Is "English". But that's just a guess.

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The results that you get on the models used on any of the platforms are only as good as the sample populations used for comparison and at present these are very limited.

The CEU,  'European population' for the HapMap project  came from Utah and was collected on the 1980s . No-one knows "how accurately these samples reflect the patterns of genetic variation in people with northern and western European ancestry."

https://hapmap.ncbi.nlm.nih.gov/citinghapmap.html

 I understand that the sample data used for British Ancestry on 23andme is thought to skewed towards Ireland  because a lot of the people who test there are Americans of Irish descent . http://isogg.org/wiki/Admixture_analyses

There is good recent data on the British Isles. It's sample population comprises people from rural areas who have 4 grand parents born within 80km of each other ( I would have been eligible with just one  grandparent from 75km away, the rest from within a very much smaller radius). This data  isn't available for use in other models.

The 2015 analysis is also behind a pay wall  but there is quite a lot of detail available online

http://www.ox.ac.uk/news/2015-03-19-who-do-you-think-you-really-are-genetic-map-british-isles

http://www.peopleofthebritishisles.org/nl6.pdf

 

 

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One of the ancestry apps on 23andMe has a cluster that is identified as Orkney, and is distinctly different from the other clusters in the British Isles.

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Some Vikings from Greenland took an Eskimo kid with them when they went home to see the folks, but he escaped.

Answer 2

I was very confused by the same finding until I read this: https://www.theguardian.com/science/2015/dec/28/origins-of-the-irish-down-to-mass-migration-ancient-dna-confirms.