Cautious Mode Cornwall Related Ancestry

[TopLobster]

In cautious mode the map of the Cornwall related group includes "South England" but skips over Devon, what is the reason for this? I would assume Devon would be genetically closer to Cornwall than South England is to Cornwall. South England is also included in the South East England related group so it seems that this is an area where the clusters overlap.

Cautious groups.PNG Cautious Cornwall group.jpg Cautious South East England group.jpg

[Angela]

In cautious mode the map of the Cornwall related group includes "South England" but skips over Devon, what is the reason for this? I would assume Devon would be genetically closer to Cornwall than South England is to Cornwall. South England is also included in the South East England related group so it seems that this is an area where the clusters overlap.

Cautious groups.PNG Cautious Cornwall group.jpg Cautious South East England group.jpg

That's odd.

I'm not an expert on English genetics, but I do remember something about Devon being slightly different than the rest of southern England, and the closest to northern French genetics. Does that ring a bell with you or am I remembering it wrong?

[TopLobster]

That's odd.

I'm not an expert on English genetics, but I do remember something about Devon being slightly different than the rest of southern England, and the closest to northern French genetics. Does that ring a bell with you or am I remembering it wrong?

I don't remember reading anything about the similarity to northern French genetics. But from this graphic, it doesn't look much different from Cornwall in terms of similarity to regions of Europe.
British Regions Similarities to European Regions.jpg

Here is the first part of the description LivingDNA gives about the confidence group:

Cornwall-related ancestry
This is a confidence group for Cornwall ancestry with small spread. It includes Cornwall and South England populations. As it is the smallest possible grouping for Cornwall and surrounding ancestry, it is very likely that your true ancestry falls inside one or both of these two populations.

[Angela]

I don't remember reading anything about the similarity to northern French genetics. But from this graphic, it doesn't look much different from Cornwall in terms of similarity to regions of Europe.
British Regions Similarities to European Regions.jpg

Here is the first part of the description LivingDNA gives about the confidence group:

Cornwall-related ancestry
This is a confidence group for Cornwall ancestry with small spread. It includes Cornwall and South England populations. As it is the smallest possible grouping for Cornwall and surrounding ancestry, it is very likely that your true ancestry falls inside one or both of these two populations.

I haven't found the French reference, but these two citations were in my folders:
http://www.ox.ac.uk/news/2015-03-19-...-british-isles

http://www.bbc.com/news/science-environment-31905764

Genetic map of England:


Just as a general proposition, I find that the "cautious" mode in any of these tests is not as accurate as the less rigorous ones, probably because in that mode they're demanding very high levels of probability from the algorithm.

[TopLobster]

Just as a general proposition, I find that the "cautious" mode in any of these tests is not as accurate as the less rigorous ones, probably because in that mode they're demanding very high levels of probability from the algorithm.

I believe "cautious" mode is the least rigorous setting on LivingDNA. It is supposed to be the most certain. Whereas "complete" is less certain because the groups are smaller and less distinct.

[elghund]

I believe "cautious" mode is the least rigorous setting on LivingDNA. It is supposed to be the most certain. Whereas "complete" is less certain because the groups are smaller and less distinct.

It seems that Cautious mode is the same as Standard mode but similar subgroups are just joined under new, more general labels.

[TopLobster]

It seems that Cautious mode is the same as Standard mode but similar subgroups are just joined under new, more general labels.

Right, but why do the region boundaries on the map change to exclude some parts. For instance, in standard mode I have 16.9 NW Scotland, 6.6 Aberdeenshire, 2.3 Ireland. In cautious mode, the NW Scotland Related group doesn't include Aberdeenshire on the map but the percentage from Aberdeenshire is included in the total for the group (16.9 + 6.6 + 2.3 = 25.8). A similar thing happens with Central England, which gets put into South East Related (17.9 + 17.5 + 7.7 + 5.1 = 48.2), and Devon, which gets put into Cornwall related (3.6 + 1.5 = 5.1) but doesn't show highlighted on the map.

LivingDNA map Standard with numbers.jpgLivingDNA map Cautious with numbers.jpg

[TopLobster]

This other version of the genetic map seems to show that Cornwall and Devon are distinguishable but the area that LivingDNA calls Southern England is part of the East and Central England cluster, so it is slightly more distant than Devon. Am I correct? I don't know how LivingDNA is able to differentiate the parts of the large Central and South East England cluster when POBI was unable to.

https://www.livingdna.com/en/help-ce...stry-breakdown

POBI Genetic Clusters.jpgPOBI 17 Genetic Clusters.jpg

[TopLobster]

I sent the following to LivingDNA Helpdesk.

Hello,
When I view my family ancestry results in cautious mode, the Cornwall related group includes Cornwall and South England, but skips over Devon. What is the reason for this? I assumed Devon is genetically closer to Cornwall than South England is to Cornwall. In the study "The fine-scale genetic structure of the British population" by Leslie et al. 2015, the area that LivingDNA labels South England seems to be part of the South East and Central England cluster. Can you try to explain this to me?

Also, when switching from Standard mode to Cautious mode, my ancestry estimate for Central England disappears from the map, but it seems as if the percentage from that region contributes to the total for South East England.

The response:

Our bioinformatics team have come back with the following information:

Devon and Cornwall historical populations are quite different to each other. Cornwall has more similarity to South England than to Devon.

Regarding the Cautious view: In this view, we have grouped the most genetically similar populations together. By being cautious and conservative about your assignments, we are most certain about these assignments of your ancestry breakdown. If you click on a region, and scroll down to its description, you will find some explanatory text. For example:

Southeast England-related ancestry
This is a confidence group* for Southeast England ancestry with small spread**. It includes Southeast England and South England populations. As it is the smallest possible grouping for Southeast England and surrounding ancestry, it is very likely that your true ancestry falls inside one or both of these two populations.

*Confidence groups are chosen so that we are confident that you have ancestry from at least one of the populations highlighted.
**Spread refers to the number of populations within the confidence group. A confidence group can be made up of 2 (small), 3 (medium), or 4 (large) similar populations.

This descriptive first paragraph will vary per confidence group and may vary per set of results; this means that your description of Southeast England-related ancestry (if you have it) may not be the same as another person's description of their Southeast England-related ancestry (if they have it).

They didn't really answer my second question. I already knew the information they wrote from reading the FAQs. I am unsatisfied.

[TopLobster]

I contacted LivingDNA Helpdesk, this is the response I recieved:

Our bioinformatics team have come back with the following information.

Devon and Cornwall historical populations are quite different to each other. Cornwall has more similarity to South England than to Devon.

Regarding the Cautious view: In this view, we have grouped the most genetically similar populations together. By being cautious and conservative about your assignments, we are most certain about these assignments of your ancestry breakdown. If you click on a region, and scroll down to its description, you will find some explanatory text. For example:

Southeast England-related ancestry
This is a confidence group* for Southeast England ancestry with small spread**. It includes Southeast England and South England populations. As it is the smallest possible grouping for Southeast England and surrounding ancestry, it is very likely that your true ancestry falls inside one or both of these two populations.

*Confidence groups are chosen so that we are confident that you have ancestry from at least one of the populations highlighted.**Spread refers to the number of populations within the confidence group. A confidence group can be made up of 2 (small), 3 (medium), or 4 (large) similar populations.

This descriptive first paragraph will vary per confidence group and may vary per set of results; this means that your description of Southeast England-related ancestry (if you have it) may not be the same as another person's description of their Southeast England-related ancestry (if they have it).

I am unsatisfied with the response to my questions regarding the map changing and not including regions that contribute to the admixture percentage. They just copy-pasted info I already read from the FAQs and it doesn't answer my questions.

[TopLobster]

I fixed part of it with image editing.