It has been proven that there is no "special" gene. Homosexuality is created from either environment or choice. I don't know the stats on pediophilia, but NAMBLA is a start. Also, someone has mentioned AIDS. I wonder what the stats are on this among priests?
EdReform has many good links on homosexuality. Ed, maybe you could give us some?
The Catholic Catechism disagrees with you:
2358 The number of men and women who have deep-seated homosexual tendencies is not negligible. They do not choose their homosexual condition; for most of them it is a trial. They must be accepted with respect, compassion, and sensitivity.
And, in 2357, the Catechism says "Its (homosexuality) psychological genesis remains largely unexplained."
Possibly environment, but possibly genetic as well.