Why are sex words our worst swearwords?

Several weeks ago Inquirer editors debated whether we should allow more dirty words in the paper. There was talk of loosening the restrictions on damn, which we've long placed in our category of lesser offenders though it implies something horrendous - condemnation to hell (a word we're also easing up on).

Topping our list of the worst possible words is the F-word, though in its literal sense it conveys something very nice. Writers are not specifically forbidden to use it but there are enough hoops to jump through that nobody has broken the F- barrier yet.

It's listed in our highest security class of obscenity, along with three synonyms for penis, two for vagina, two slang terms for oral sex, two variants on animal waste products and one expression that employs the F-word in an oedipal context.

What does this say about our society, and is there any scientific explanation for why people yell out a word for sex when they stub their toes?
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