/lit/ - Literature

I've been really into milf porn ever since I started watching HBO's Rome. Ceaser's niece is this hot redhead milf who is constantly showing her tits and I really want to bang her. It's odd how fetishes can come and go like that--a week ago I was jacking off to regular porn and now I want to penetrate a mature slut. I always assumed fetishes were static, either you had them for life or you didn't have them at all, but I'm beginning to think they are not at all static but rather can be triggered by external stimuli. I've had "phases" of fetish porn: lesbian feet licking, pissing, milfs, chicks with dicks, but on an average day none of that stuff appeals to me. But I see one hot older lady getting plowed on a TV show and suddenly that's all I can get a boner thinking about. It's almost like if the idea weren't presented to me I would have never thought of it. Are there some books or articles that explain this shit?