Ugh, you people and your social relativism. Sure, we could call absolutely every belief we have into question, because we've got no real frame of reference on which we could base our definitions of "good" and "evil" (unless you're a theist, but then you'd have to prove that your religion is truth, good luck with that).
I could ask "Why is it bad to kill people?", "Why is it bad to steal?", "Why is it bad to sleep with my neighbor's wife?", It's only your foolish social taboos based on the Judeo-Christian belief system that makes these things wrong.
For anything to be logically deduced to be good or bad, we have to first define good and bad, however, as soon as we do that, there are some people who will disagree with our definition, and we'll have to accept that they have their "good" and we have ours, and we have to tolerate their good because it's just as valid as ours; they're both products of social conditioning, and not based on any true, objective, scale of right or wrong.
But honestly, doesn't this kind of thinking digust you? I'm sorry, but I find I have to believe that some things are good and some things are evil, absolutely, not simply as a result of my social conditioning.
Sorry, pedophelia is wrong. Actually, come to think of it, I'm not at all sorry. Pedophelia is wrong.