What are the origins of the infamous "totalitarian genes" theory that alleged that Russians, Serbs, Belorussians had genes favoring totalitarianism and autharitarian government, so to protect democracy those people should be restricted and/or eliminated; and which has been used to justify the restriction of the rights of ethnic Russians in the Baltic states?
I have never heard this theory, and I suspect it's rooted in racism from victors who want to get rid of their enemies. I do not think it has any basis in science or biology.
You might as well ask about the theory that Jews have deceitful genes and bad blood that will make them treacherous, another thinly cloaked racist pseudotheory.
You might be better placed than most to dig up an answer to that one. Here in the USA, I have never heard that one before. My guess is its a modern invention in a specific area (and thus probably isn't really "History").
Such arguments in the USA generally revolve around culture, not genes. The idea being that Despotic Culture X goes back thousands of years, and thus the people there don't know any better, and even if someone handed them a Democracy they'd have no idea how to run it properly and wouldn't appreciate it at all.
I still think they are wrong. Such people move here all the time, and I play soccer (and have beers afterwards) with them. In my experience, nobody loves freedom more than an immigrant who grew up behind the Iron Curtain. (Arab-Americans come a close second).