This question is meant respectfully, not to trip you up, and I won't think bad of you if you don't know the answer.
I understand that priests may be married in the Eastern rite Catholic churches, but not in Latin rite Catholic churches. Except that the Vatican, according to news accounts, does not allow married Eastern rite priests in countries like the U.S. where the Latin rite predominates. What is the theological reason for this?
Of course, it could be that in a perfect world the Eastern rite would adopt the Latin rite practice. Also, I'm pretty sure that a married Eastern rite priest is not going to become a Cardinal, since I never heard of a married Cardinal, so, obviously, the Eastern rite also encourages celibacy.
There was an informal agreement until a few years ago that Eastern Rite priests in the U.S. would be celibate as a general rule (obviously unenforceable for already-married immigrants). The Eastern Rite bishops then announced they would no longer accede to this expectation of the U.S. Latin Rite bishops.
As another poster has already noted, all Catholic bishops must be celibate, whether Eastern or Latin. Marriage remains optional for Eastern Rite clergy. Theologically, where the Church does not require celibacy for priests (Eastern Rite) the charism, or grace, of chaste celibacy may or may not be given and the call to the married or celibate state of life must be discerned by the candidate.
If they are going to marry, candidates for priesthood in the Eastern Rite must be married before receiving Major Orders (the diaconate and the priesthood). They may not marry after being ordained. (This also applies to Permanent Deacons in the Latin Rite. It seems a good rule; how awful to imagine a pastor eyeing his flock with wedding bells ringing in his ears....)
The answer is, that special charisms of this sort are given for the benefit of the Church (the whole Church or part of it), not the individual -- just as being understood by foreigners of another tongue, or just as prophecy (private revelation) also may be. The charism does not depend upon the individual (except they be disposed to receive it) but the needs of the Church.
The Holy Spirit responds to the need of the Church for celibate priests by manifesting the Gift of Celibacy within individuals, so they may answer their vocation and live it faithfully, for the greater glory of God.
(Testosterone levels are irrelevant -- apropos a different poster.)