Welsh specific genetic drift

[avalon]

I thought these were some interesting Welsh related snippets from recent preprint on blood pressure genes. http://biorxiv.org/content/early/2016/05/27/055855

No ancient samples were found to vary along the Welsh-specific axis, suggesting that the Welsh populations differ from the rest of the UK due to drift and not different levels of admixture.

Additionally, the lack of any ancient sample correlation with PC2 suggests that Welsh populations are not differentially admixed with any ancient population in our data set, and
likely underwent Welsh-specific genetic drift. We confirmed these findings by projecting pan-European POPRES samples onto the UK Biobank PCs noting that of the continental European populations, Russians (who have the most Steppe ancestry) lie on one side and Spanish and Italians (who have least) lie on the other side along PC1 and PC3, and that none of the continental European populations projected on to the same regions as the Welsh on PC2 and PC5.

I don't pretend to fully understand the process of genetic drift but my understanding is that it tends to occur in small populations which would fit with Wales, ie. a small country, mostly difficult terrain and lightly populated throughout history. Also, this explanation of drift might go some way to explaining the the results of the recent PoBI paper in which the Welsh showed a noticeable level of genetic separation from the rest of the UK.

[AJL]

Interesting, I was musing a while back that there might be drift among Welsh people based on my autosomal matches. Thanks for that.

[avalon]

Interesting, I was musing a while back that there might be drift among Welsh people based on my autosomal matches. Thanks for that.

Good observation, I hadn't seen that thread. I have heard a couple of people on this forum hint at some sort of Welsh drift but this is the first time I have seen it mentioned in a scientific paper.

[JonikW]

Interesting, I was musing a while back that there might be drift among Welsh people based on my autosomal matches. Thanks for that.

I wonder whether this Welsh drift could have anything to do with why four of my 10 closest matches on 23andme match me on both my paternal and maternal sides. Or is that just down to the relatively small population? My mother was from the Valleys, while my paternal grandmother had roots in the Black Mountains. So they were from neighbouring populations rather than the same immediate area. Three of those matches are across three segments (0.32%, 0.31% and 0.25% shared) and the other is across two segments (0.45% shared). By way of comparison, a 0.59% match on three segments who matched only on my Mother's side turned out to have the same great, great grandfather as me, born at Llanfair Discoed, Monmouthshire, in the 1820s). Intriguing anyway...

[jdean]

My mother is approximately 90% Welsh & 10% English

She picks up a lot more FF matches than my father who is 10% Welsh & 90% English and most of these folk have at least one generic Welsh name in their family tree.

Unfortunately I've never been able to help any of them save suggesting they likely have S. Wales ancestry with a bias to the SE because though I've managed to trace the surnames of 30 of her 32 3x great grandparents, and also place of birth for most of them, she only has 19 unique surnames plus I would imagine it very hard for most Americans to trace the origin (this side of the pond) of any ancestor who shared one or two of her Welsh surnames.

[JohnHowellsTyrfro]

Worth remembering maybe that before the industrial revolution the population of Wales was only about 500,000 and that people in the more remote and agriculture-based communities probably didn't travel that far for the most part. I would guess that this would apply even more to the particularly remote places like Snowdonia.
It's a bit of a standing joke that if you meet a Welsh person for the first time, within 10 minutes they will have your life history and know how you are related. John

[jdean]

Worth remembering maybe that before the industrial revolution the population of Wales was only about 500,000 and that people in the more remote and agriculture-based communities probably didn't travel that far for the most part. I would guess that this would apply even more to the particularly remote places like Snowdonia.
It's a bit of a standing joke that if you meet a Welsh person for the first time, within 10 minutes they will have your life history and know how you are related. John

Out of curiosity have you got a Jennifer Stedman in your matches ?

[jdean]

Out of curiosity have you got a Jennifer Stedman in your matches ?

Ha : ))))

No worries, I can see you !!

'4th Cousin - Remote Cousin', now what would be the odds of that I wonder.

Pretty high I should imagine : )))))

[JonikW]

Ha : ))))

No worries, I can see you !!

'4th Cousin - Remote Cousin', now what would be the odds of that I wonder.

Pretty high I should imagine : )))))

Or maybe not based on my experience

[jdean]

Ha : ))))

No worries, I can see you !!

'4th Cousin - Remote Cousin', now what would be the odds of that I wonder.

Pretty high I should imagine : )))))

Sorry my mistake, this is the match with me, Mum's down as '5th Cousin - Remote Cousin' so presumably some of Dad's Welsh ancestry is kicking in to make us closer. He on the other hand isn't a match which again isn't too much of a surprise.

BTW Though Dad's genetic make up is 90% English and 10% Welsh he's also Welsh, he was born in Talywain like his father and his mother came from Merthyr