Ignoring the question? ... If GOD is required to use a gamete/female sex cell from Mary in your catholiciism calculus, where did the male gamete come from?
I do know that there had to be a female gamete from Mary.
I know that the Messiah had to be "born of a woman, born under the law" as St. Paul said (Galatians 4:4). So He had to have a natural human mother.
I also know He had to be "the seed of the woman" (Genesis 5:15). To be her seed, He must be the true natural Child of His mother, and beyond that, the true natural descendant of His ancestors, in the full sense of the word.
And the whole point of the genealogies, is that His mother Mary linked Him to His whole constellation of human kinship going back in an unbroken chain of generation to David, to Abraham, to Noah, to Adam and Eve. This tremendous epic of Divine Providence loses its entire significance if the "chain" breaks when it comes to Mary.
And what was God doing through the whole "family story" of the O.T.? Generation after generation, He was preparing this pure seed that would constitute the body of His Christ: "When Christ came into the world, he said: "Sacrifice and offering you did not desire, but a body you prepared for me." (Hebrews 10:4).
Thus God brought true natural offspring to all through whom the Messiah would come: "The Lord God has sworn to David in truth and he will not turn from it: 'One from the fruits of your loins I shall set upon your throne.'" (Psalm 132:11).
So Mary's gamete--- which means ovum --- which means "seed" --- is not an incidental or technical detail here. It is the fulfillment of several thousands years of providence and prophecy. May God be glorified forever.
As for sperm? I don't know. Maybe God created a male gamete? Maybe He quickened her (female) seed to produce a (male) Son in a way entirely unknown to us? That part is shrouded in complete mystery, before which I can only bow in reverent silence.