Clearly a virgin birth is parthenogenetic. This is normally not likely in human beings, but one could argue for its possibility with Divine Intervention. But parthenogenetic offspring are female, necessarily.
On the other hand, the Christian god is not incarnate until after the parthenogenesis takes, so in its previous, spiritual state, it could not have supplied a sperm cell (which is flesh, not spirit). Moreover, as Rome has made clear, the Christian god's whimsy is restricted by its rationality and obedience to its own limitations (unlike the Muslim god; not clear about the Hebrew god). Then too, how many miracles can one have in one event? To get a parthenogenetically engendered boy-baby would have taken three or four in quick sequence; there is a parsimony problem, and a rational deity would not commit such an irrationality.
At least, not among Christians. [One could argue that for Jews, the deity can be quite irrational; read his dealing with Ezekiel, Samuel and Saul, and Solomon. Muslims admit their god is capricious at least, certainly not rational; one is not sure how to take that. In these religions, of course, their gods are clearly capable of working as many miraculous suspensions of Natural Law as are needed to get the job done.]
There may even be scriptural warrant for this, in the Secret Gospel of Mark, the existence of which is attested in a letter of Clement, now missing but seen by two reliable witnesses and photographed — admittedly, in a late copy. It the interesting passage, Lazarus (clearly a buddy of Jesus) spends the night with her — or him. There don't seem to be any other records of Jesus making it with other folks. One could maintain Jesus was an abstinent homosexual, but Clement is clear, this is not so. The alternative? Lazarus and Jesus -- who was normally a cross-dresser, so she would be taken seriously in a patriarchal world — had a Thing going.
This is a good argument for women in the priesthood, don't you think? And there is the germ of an interesting heresy, too. Of course, it does leave Bishop Robinson out in the cold, still....
But the effect on Nigerian bishops could be wonderful. Think of all the shades of red they might turn (or, purple sufficient to match their clerical garb), when one told 'em "Jesus was a gurl!"