My dear friend, not so long ago, homosexuality was in the DSM as well. The DSM definitions are not the word of God; they reflect social conventions and not scientific eternity. Ditto about what counts as criminal behavior (gay sex was an offense until 1980 in Israel: does this mean it was not moral until then? Bullshit).

The difference between gay behavior and paedophilia lies in the exploitative, coercive nature of the latter, and in the fact that the former is not prohibited as long as it is done by adults out of mutual consent. Don't bring the DSM or the criminal law into this. It's really, REALLY, a very bad argument for anything.

Folks might find Conrad and Schneider's book "From Badness to Sickness: Deviance and Medicalization" of interest. It's one of my favorite books about framing social problems.