Getting it taught in schools--sex education first, which we have had as long ago as the fifties, and then all the deviations later--is part of the plan of eradicating Western culture. It is not something that came along recently. It is cultural communism.
While I don't doubt for a moment that the left will use anything it can to undermine western culture sexual obsession was around a long time before Marxism. And any Marxist who is among the sexually obsessed will be dominated by that obsession and not the ideology. The use of sexual deviancy as a tool to undermine Judeo-Christian mores and cultural underpinnings is not a case of creating a new tool but, I think, a case of taking advantage of a tool that was already to hand. The left has simply given these people legitimacy and a platform from which to speak and spread their agenda. It's a sort of "enemy of my enemy" thing.