Any uninvested reading of the Gospels make them mutually exclusive in many respects, so the fact that only Matt. and Luke deal with Mary’s virginity is obviously no more troubling theologically than the myriad other inconsitencies between them. Mark skips the infancy altogether, does not even mention Jospeh by name, and barely makes reference to Mary the mother. As Matt. and Luke are thought to have drawn from Mark, Q, and sources unique to Matt. and Luke, the Virgin Birth must have been a relatively early and widespread tradition, I should think. John might be more troubling, given the weight of importance he places on Jesus’ spiritual nature, but, again, he has nothing to say about Jesus’ early life, except that he’s the son of Joseph (Mary the mother is not even identified by name, whilst three other Maries are), and seems not concerned with it. What are we to make of the fact that Mark does not name Jospeh, and perhaps more remarkably, that John does not name Mary the mother? I make of it they felt no need to expound on that part of the tradition.
But the case of Paul is most interesting, both theologically, and historically, and you indeed point out a glaring error in my recollection.
Paul harps on, esp. in Romans, Christ’s divinity, e.g. he was born “in the likeness of sinful flesh”, but he’s also identified as the “seed of David”. You’re right, Paul makes no mention of the Virgin birth, and may even contradict it. Not sure why I remember it otherwise. I guess the divinity seemed so important to him that somewhere along the line I took it for granted he must have believed Mary to have been made pregnant through the miracle of the Holy Spirit. According to Luke (contradicting Matt., of course), Jesus is an ancestor of David through Mary as well as Joseph, but Luke comes some forty years after Paul’s letters, at any rate, so it’s difficult to draw from the Lukan tradition to speculate about what Paul may have understood. One would reasonably infer from the “seed of David” comment that to Paul, a Jew with a Jewish perspective, Jesus’ descent from King David was patrilineal.
In reflection, I guess it could be argued the Davidic lineage should be far more important for Jesus’ purported messianic role than any miracle of parthenogenesis, and it’s interesting only two Gospels seek to draw attention to it, given how old the notion must be. That those same two Gospels are the source of the Virgin Birth tradition makes it all the more interesting. I forget so much, including how fascinating these mysteries are.