Unfortunately the Lamnidis et al. 2018 did not test the origin of the Siberian ancestry in present-day Finns and Russians. I reveal it now. Ancient samples found from Bolshoy gives high F3-results for both groups. I included five Finnish groups, three of my own sample selection and two smaller selections from two academic sources.
FinnMostCW - least drifted Finnish group (- outliers)
FinnLocal - most drifted Finnish group (- outliers)
Finn21M - most Scandinavian group (- outliers)
Both academic Finnish groups look incoherent. I wonder why.
It is obvious that the Levaluhta admixture added to the present-day European backbone in Finns (negative F3-values) doesn't explain all non-Europeanness and there have to be an unknown third component.
Source1, source2, target, f_3, std.err, Z and SNP count
Additionally, here are resultw of my old admixture analysis based on Dna.Land's program. Although it sounds a weird idea to make admixture analysis of ancient samples using present-day populations, it is a normal practice in many academic studies. Studies usually use Nganasans to represent Siberians together with ancient samples. It is reasonable to say that the gene flow can be detected also backwards. It is also very likely that the gene flow between contemporary populations has been bidirectional. Nevertheless, I am not fully convinced about the gene flow direction regarding the European side of Finns and Northern Russians. F3-statistics gave several European candidates and the big picture is more complex.
Levaluhta (JK excluding JK2065 outlier)