These genetic studies are not be very persuasive to me as I imagine that:
(1) The invading Brahmins, if they existed, were not very different genetically from the natives they were conquering and no doubt (being mainly male warrior types), raping.
AND
(2) The invading Brahmins were greatly out numbered by the natives. In less than 30 generations, the “Indian gene pool” would have their genes uniformly distributed in it.
I know much to little about all this to be confident in the above, and do know there is some weak genetic evidence for Genghis Kahn’s army* was in the Balkans or at least somewhere on the East side of Caspian Sea but those areas were not a fully populated and that was more recent.
I had never heard of the "Aryan theory" but suspect this is just an effort for misguided Brahmins to "elevate" their origins. Perhaps they were just driven down form Kashmir by a sequence of harsh winters. (We can call this the "Abominable snowman" theory of Brahmin origins.
) Certainly Hitler would have no trouble of sending the Brahmins to gas chambers as "non-Arians" and in this, I status judgment, I support Hitler, but not his probable acts towards Brahmins.
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*It came from much farther way and thus was very different genetically form populatin being invaded and raped, than the invading Brahmins. I understand these Brahmins were non-Aryans, from only a 1000 or less miles away.