From books I've read, I think that usually when they tell about incestual behavior it's to point out that certain characters are bottomfeeders. Abuse tells you that there's a crime involved here....and these behaviors could do what the rape scene in Girl with the Dragon Tattoo did, set up the whole reason that the story happened...absolutely necessary, and the book had a lot of other stuff in it besides the rape itself.
Closest I came to getting disgusted was reading a "love scene" with "nudity" between a couple of normal hormonal 13-14 year olds where no crime was committed. I figured the author was just plain desperate. It was enough that the adults were weird - all of them looking at or coveting somebody else's mate, if not fornicating or committing adultery, or all of the above, seemingly the whole reason for the book, to titillate......
I sort of remember feeling like you do, when I was more idealistic. People I've admired let me down, and it seems that sex was just invented, all kinds, and everybody wants to try it out...the hell with real love...
Let us know what book got you ticked off. You could start a good conversation or book discussion inadvertently..
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