The narrative and the context indicate that this is what happened. Mary was confused and wondered how that was supposed to work (not that she disbelieved Gabriel, she just couldn't think of the methodology). Furthermore, Joseph naturally could not have imagined how this could have happened [outside her having relations with another man], so he needed to be clued in as well.
Thus the "central tenant" is believing the text. Now of course in modern times virgin births can be had through IFV. Nobody would think twice about how that could happen, and nobody would claim that the children conceived by means of doctors and lab technicians are gods. Half the chromosomes come from the father, but are directed to the egg a different way.
Yet who even considers that it was Joseph's chromosomes that could come to Mary by means of the Holy Spirit to cause the conception of a child. The assumption is that Jesus is some mysterious man-god hybrid, because that's what people came up with themselves to explain (!) what they couldn't understand. Mary had the sense to inquire. And Joseph was righteous, not wanting to embarrass Mary, but as is the way with men, they just aren't wired to stop and ask for directions, so an angel of the Lord told him. By means of the Holy Spirit. And he believed it. Ah, what a relief then, because something didn't add up.. Mary just didn't seem the type..
Son of David. Through Joseph the son of David. Son to son to son, as it should be, as was promised to David. But if people don't really believe the promises of God, then they've got to create all sorts of clever arguments and justifications to explain their own ideas that make no sense. Keeps the house of merchandise in business.
If it was Joseph’s chromosomes that eventually made up Jesus’ other DNA half, why did Mary ask how it was that she would be with child? Wouldn’t she expect Joseph would be the father by the usual, natural means?