Celibacy is a choice. Sexual orientation is not. Asexuals are sometimes celibate because it fulfills their natural experiece of having no attraction. It is bisexuals that can go either way. Asexuality is similar to the Platonic sexual ideal upon which celibacy is based. It is also likely that St. Paul was Asexual (it was not a job requirement for him). We assume he taught purity because of the imminent return of Christ, but it may have been an artificat of his own innate sexuality. The pattern continues.