This prominence, however, contrasts with the apparent reticence of the New Testament authors to discuss the topic and their circumspection while doing so. It is narrated or mentioned independently in both the Matthean and Lukan Infancy Narratives, and nowhere else. Moreover, comparisons with partial "parallels" in pagan literature, such as the supposed conceptions of Alexander the Great (Plutarch, Alexander, 2) and Plato (Diogenes Laertius, 3.2) are notable in that only the New Testament accounts affirm parthenogenesis—conception without a male element—in a strict sense.
Theologically, there is no ground for the common claim that the virginal conception was necessary to protect Jesus from inheriting the guilt and/or corruption of "original sin." Nor—and this is a point that must be developed at a later time—are there firm exegetical grounds for claiming necessity based on the need to "fulfill" predictive "prophecy." At the most basic level, we can affirm that this was the chosen means whereby God brought about the incarnation of his Son. More profoundly, Karl Barth helpfully suggested that it was a sign pointing to the mysterious unity of divinity and humanity in the person of Jesus of Nazareth (cf. Barth, Church Dogmatics, IV/1, 207).
But what of the historicity of the event? Nowhere, I suppose, do preunderstandings and presuppositions play a greater role than in matters such as these. There is, of course, no way to prove that Jesus was born of a virgin by means of the canons of modernist, positivist historiography. Skepticism about such outrageous claims is likewise healthy. Nevertheless, it is likewise silly to claim, as many skeptics continue to do, that we in this scientific age, unlike those poor, benighted ancients, know that such things don't and can't occur. Even a cursory examination of both Matthew and Luke will reveal that is not the case.
Can a convincing, or even plausible, historical case be made? You must be the judge, though Professor Wright argues that indeed one can. The same can be said of an older British theologian and New Testament scholar, Charles E. B. Cranfield, who concluded in a penetrating article on the subject ("Some Reflections on the Subject of the Virgin Birth," Scottish Journal of Theology 41  177-89 ) thus:
It is, surely, extremely difficult, on the assumption that the Virgin Birth is not historical, to explain at all convincingly how the early church came during the first century to affirm it, in spite of the fact that there was no expectation that the Messiah would be virgin-born, in spite of the certainty that such an affirmation would be met by ridicule among the Jews, in spite of the church's own interest in maintaining the Davidic descent of Jesus, and in spite of the obvious danger that among Gentiles the doctrine would be misunderstood along the lines of pagan mythology. The arguments for rejecting the historicity of the Virgin Birth seem to me, as I examine them yet again, not nearly as strong as they are often assumed to be, and the arguments for accepting it seem to me weighty. I have to declare myself convinced that I can, without violating my intellectual integrity, affirm with the Apostles' Creed, ex animo, without mental reservations and without shuffling, that Jesus Christ "was conceived by the Holy Ghost, born of the Virgin Mary.