I think the absence of sex in Salinger's work was because he was a pedophile.
http://www.slate.com/id/2243564
Something about the character of Seymour always made me think that, although it's been so long since I read any of Salinger's work, I can't fully recall, and am perhaps too lazy to go back and lay it all out, but at the time, I remember reading him and thinking "Huh. WTF?" I think Seymour was a projection of Salinger himself, more than even most characters are with writers, and I think that might account for why Salinger was so reclusive and paranoiac, and why the only interview he granted was to those high school students in the early 70s. I think Salinger liked kids. Maybe REALLY liked'em. His estate is surely keen to control the legacy of his work (whatever that precisely is), so, like Jacko, it'll be something that's camouflaged, explained away, and/or concealed. But still, it makes me wonder.
