Serious sexual repression I think. Conservatives publicly treat sex and sexuality as things that are dirty and sinful. Sometimes they get caught out for doing weird shit because they can't escape from their inherent human sexual urges.
I think that also contributes to their raging LGBTphobia. They think we're just a kink or a fetish, because that's how they view all intimacy. It's projection.
I honestly think a lot of it is probably rooted in childhood and generational trauma (e.g. their parent(s) physically/verbally abused them for sexual curiosity at a young age, just as their grandparents' did to their parents, and so on).
As my friends who specialize in trauma therapy like to say, a majority of the weird/evil shit we see in the world is rooted in trauma.