"Some things ARE offensive"

Earlier today I finished reading On The Pornographic Imagination, and I'm now about 50 pages into Reading Lolita in Tehran. I just got to the part where the class is discussing the censorship and the book, and one of the girls states "Some things are offensive to some people." This really stood out to me, as did a part of the Pornographic Imagination that states The Story of O (which I haven't read) and others suggest that "the obscene is a primal notion of human consciousness, something much more profound than the backwash of a sick society's aversion to the body." This is a really interesting suggestion to me- I don't think the sick feeling in the pit of my stomach when I imagine what it would be like to be raped is society's doing. I don't find the idea of fantasy/role playing/ group sex offensive, but I am offended by the objectification of women, although not in milder senses, like popular rap songs (desensitization much?) And I think aversion to things like the later are natural, while dislike of the former is learned. I'm interested to hear other people's opinions on this- are we born with a natural aversion to "the obscene" or do we learn it?