Genetics and linguistics are not always coincident.
Nothing could be more true. My veiled criticism is not because of this. It's due to the fact that when coming to certain conclusions all interested scholars should participate. But it is too early; they are still not talking to each other.
" We provide insights into the Mycenaean period of the Aegean by documenting variation in the proportion of steppe ancestry (including some individuals who lack it altogether), and finding no evidence for systematic differences in steppe ancestry among social strata, such as those of the elite buried at the Palace of Nestor in Pylos."
It has some important points, we know about the lack of Iranian-related ancestry among the Etruscans who had a very high amount of steppe related ancestry, Etruscans had some relatives in Greece, like Lemnians.
All true, except that "Lemnians" are not existent. Or rather, archaeology has found a couple of inscriptions in Lemnos that have turned out to be related to the Etruscan language, but unlike with the Alpine Rhaetians, there is no archaeological culture in Lemnos that shows correlation with the Etruscans (in contrast, the archaeological culture of the Rhaetians on the one hand is distinct from that of the Etruscans, on the other hand it shows relationships). This is why archaeologists and some linguists, even before the latest genetic studies, thought that the presence of a couple of Etruscan-related inscriptions were due to movements of small groups of Etruscans from Italy, particularly from southern Etruria (Cerveteri or Veio in Lazio) to Lemnos who maintained the use of the Etruscan language that changed over time to become distinct anyway, absorbed by the local population, who may have been Thracian in origin. Then the island of Lemnos around 500 B.C. was conquered by the Athenian Greeks.
Etruscans did not lack the Iranian-related ancestry, they are actually part of the Mediterranean continuum (minoans to Republican era Romans) who are distinguished by having Anatolian_N + CHG. The steppe component is a minority component, albeit an important one. But also, the Etruscans are not related to Lemnians, the Etruscans were shown to be autochthonous.
Take a look at admixture proportions, there is indeed Iran-related ancestry. In fact it is comparable to their Eneolithic steppe ancestry. From the study Antonio et al. 2019.
Etruscans did lack the Iranian-related ancestry according to the studies, it is indeed the conclusion for the Etruscans of Posth 2021. In the chart you've posted the other component is EHG, not Steppe, it's comparable to their Eneolitich EHG ancestry, and the sample includes also Latins, a Protovillanovan sample from Abruzzo and the outliers with non-native ancestry. Let's not confuse when geneticists use Iran_N instead of CHG in relation to Steppe, all ancient Europeans can be modeled with Iran_N instead of CHG + EHG. Iran_N uncoupled to a Steppe source, as found in the Minoans, is a different story.
Both Etruscans and Latins, who had a very similar genetic profile, are composed of WHG, EEF and Steppe (30 percent according to Antonio 2019, 25 percent according to the 2021 study, so between a third and a quarter of their genome, not exactly little).
Mediterranean is a geographical concept first and foremost. If we consider everything from southern France/Iberian Peninsula to the Aegean to be Mediterranean, however, significant differences remain between Etruscans/Latins on the one hand, and Mycenaeans/Minoans on the other, and are the differences that still exist today between the southwestern European cluster and the non-Slavic southeastern European cluster.
The "Mediterranean" stratum (or Old Europe as it was named by Marija Gimbutas) in the Etruscans as in the Latins is the ancient stratum that has characterized Western Europe since the Chalcolithic (when it emerges that the Farmers have mixed somewhat with the WHGs of the Mesolithic), while in the Mycenaeans and Minoans, the lack of WHG and the presence of extra Iran_N compared to a Steppe-type source make them from the beginning a more typical southern Eastern European population.
Not to mention the uniparental markers, especially males, which suggest completely different ethnogenesis. The Etruscans as well as the Latins with dominant R1b is as if they were the fusion on a par of an R1b-driven north-central European population, migrated to Italy during the Bronze age, with the G2a-driven Chalcolithic local population. For the Mycenaeans we await further analyzed samples, but those few published so far suggest completely different routes.