Ahh, your 'solid scientific reasoning' returns!
Otherwise known as "what I say can be accepted as informal fact, but any statement by you should be treated like a legal accusation and be proven beyond reasonable doubt with citations and footnotes, even for expressions, generalisations, figures of speech and metaphors not actually essential to any point under discussion." This is wearying beyond belief.
...did you literally not read my post? You're just repeating things I already said. I mean, compare for example your "they don't form nearly the majority" with my "I'm not saying the language always matches the majority genetic heritage of a group". It's hard to believe you're missing the point that much accidentally - is this some sort of mockery I'm not getting?
The 8% and 5% proportions of eastern genes are clearly there but at the same time they don't form nearly the majority of the Finnic genetic ancestry. They are the part which you can identify with the people who brought the Uralic languages to the shores of the Baltic Sea. The language certainly came from the east. The rest of the genetic ancestry of the people points to other routes into the country, though. These people must have spoken other languages which their descendants, including the present population, have since lost. That right there is language shift, a large proportion of the population acquiring a first language which was foreign for their ancestors.
Also, no - this scenario does not imply "a large proportion of the population acquiring a first language which was foreign for their ancestors" in any meaningful way. Unless you call, say, a Finnish person marrying a Swedish person and teaching their children Finnish a "language shift". Because again, ancestry is not a matter of monolithic races. You have two parents, and four grandparents, and so on: so you can 'acquire a language your ancestors didn't speak' while at the same time 'continuing to speak the language your ancestors spoke', if your ancestors spoke multiple languages. NOTA BENE: saying you have 8% uralic genes does not mean that 8% of the population is Uralic and the other 92% are non-Uralic and must have shifted their language. It means that on average 8% of your ancestors were Uralic (well, not exactly, but that's a lot closer). In the case of the Finns, Y-DNA demonstrates that the vast majority of Finns are directly descended from the people who brought Finnish to Finland (and from other people). The people who came to Finland didn't have a language-shift; their children, learning their father's language, didn't have a language-shift; their children, learning their father's language, didn't have a language shift; their children, learning their father's language, didn't have a language shift.
Let's give a simplified little example. Let's say a population starts out with 10 orange people and 90 purple people. Let's say that the orange people reproduce at a rate of 1.8 children per person, always breeding with a purple person. Let's say that the purple people reproduce at a rate of 0.9 children per person (i.e. half the rate), always breeding with a purple person. Let's run this simulation for five generations. What happens? Well, we end up with 189 "orange people" and 53 "purple people". Let's say that everyone learns the language of their father. So, we end up with a population in which 78% of people speak Orange, and only 22% of people speak Purple. But what do their autosomal genes look like? The purple people are still 100% purple, but the "orange people" are by now only just over 3% "orange" in their genes. So we have a population in which 80% of people speak, let's call it, "Finnish", and every one of them learnt that language from birth from a parent, and yet they are only 3% autosomally let's call it 'Siberian" in their ancestry. And yet, one could hardly reasonably say that any "language shift" had taken place - everyone just learnt the language of at least one parent. Of course, in reality the situation would have been a little more complicated in terms of intermarriages and bilingualism and whatnot, and it presumably happened more gradually over time, but you get my point, hopefully: where one population sexually outcompetes another (as the dominance of N1 lineages in Finland proves was the case there), a small genetic contribution can lead to the dominance of one language over another even with pure parent-to-child linguistic inheritence. [as for that 20% relict population - in this simulation they're only 7% of the population two generations later. Presumably you wouldn't call the linguistic conversion of 7% of the population a 'language shift'...]
So, while for the purposes of this discussion we've define language shift to exclude the case where there is ANY significant genetic influence, it should also be obvious that the Finnish case doesn't even meet the much broader definition that calls 'language shift' whenever there is anything less than perfect parent-to-child transmission.
Nobody has claimed that you can. But I would say that it's misleading to think of 'your ancestors' as being just one group of people: again, ethnicities in reality are not monolithic races. And my point is that it's extremely rare for your (collective) linguistic ancestors not to be at least some of your (collective) genetic ancestors. As opposed to your/WE's contention that knowing your genetic ancestors is almost insignificant in knowing your linguistic ancestors. On the contrary, while I accept that from seeing a, say, genetically 50% IE and 50% uralic population, you can't be sure whether they speak IE or Uralic, you can be very confident that they probably speak one or the other, and not, say, Austronesian. Not 100% confident, but at least 95% confident... Certainly not, as WE would have it, almost 0% confident.I don't think that anyone is denying the importance of migrations to the spread of languages. The real data, as I'm aware, simply suggests that you can't blindly identify your genetic and linguistic ancestors as the same people.
This is not the first time we've discussed these questions, and the context of this very thread is very visible here. I think it's entirely legitimate to point out the naive and overly essentialist assumptions that underpin these ideas.I think it's quite unnecessary to invoke ideas such as "pure and uncontaminated" genes or "white european credentials". Nothing good or productive lies that way and surely no one else has brought them up.
EDIT: but whatever. No headway is likely to be made here.