On interesting question in this area is what counts as an "orientation." Are there two orientations, straight and gay, are there three, straight, day and bi, does a preference for group sex count, or a preference for multiple partners or one partner? Does bestiality and pedophilia count?
The reason I bring this us is that defense of gay relationships typically goes something like this.
1. A sexual orientation is, in many cases an unchangeable fact about a person that can't be altered by the use of free will.
2. If a person has an orientation, then a person has a moral right to an intimate life in accordance with that orientation. Celibacy should not be morally enforced on someone.
3. If one's orientation is homosexual, and this can't be changed then one should have the right to express that orientation in an intimate relationship, and society (and the institution of marriage) should recognize this fact.
But I think few of us, apart from members of NAMBLA, would use that argument in defense of, let's say, pedophilia. It seems that if you are a pedophile, and you can't change that "orientation," given the degree of harm that that does, you are morally obligated to be celibate.