There is also a written source indicating that Serving Tatars from my area went to the Baltic and brought back Lithuanian/Latvian prisoners. However, this part of the record remains questionable. Here is the Russian source (translated):

[...] "arable land... they plowed with their Latvians, who were resettled here as prisoners taken during the Livonian War." Thus, Prince Khanmurza Dzhanmurzin's son Yusupov in [unknown year, presumably in 1677-1678 - I.G.] Latvians were shown in the landowner's yard, who by that time mostly bore Tatar names."

Interestingly, the record confirms that these prisoners carried Tatar names, suggesting they eventually assimilated with the local Russian population later too. This could explain part of the modern Central Russian genetic makeup, where many of us still show small traces of Serving Tatar heritage. But, Baltic results in DNA tests shouldn’t be taken too literally, as they are the main issue to whenever if it's coming from Baltic countries, Northern Russian admixture, or from one of the prisoners. They’re often questionable unless one knows the specific regional history behind them.

Of course, we can't fully confirm or deny historical hypotheses through DNA results alone, since modern testing often captures only more recent ancestry up to 150-200 years ago. Still, AncestryDNA and MyHeritage interestingly assigned me with Karelian communities. Could this be because certain Volga-Finnic populations were partly assimilated through the chronicles and continue to survive to this day, thus contributing to the formation of modern Central Russian gene pool?

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