I’d like to point something out here: The idea that pogroms could reduce birth defects in a population is not one that deserves either derision or support without scientific evidence either way.
Of course, the idea is most likely used to support some sort of racist agenda, but the agenda/offensivness doesn’t matter. The OP’s friend or the OP should post some sort of evidence, either for or against, or a proposed mechanism, etc. Until then, there isn’t really anything to discuss. WAGs and proclamations that it can’t be true or attacks on the probable political views of the person who said it are not the sort of thing suited to answering the post in GQ.
And to the OP, if you want to make fun of the idea, GD or MPSIMS or whatever is fine. I think the theory is worthy of a little investigation – do you have any more detail that would lend itself to a more factual investigation of the topic?