...Because I am convinced that the creator God raised Jesus bodily from the dead, and because I am convinced that Jesus was and is the embodiment of this God, Israel's God, my worldview is forced to reactivate various things in the suspense account, the birth narratives included.
There are indeed more things in heaven and earth than are dreamed of in post-Enlightenment metaphysics. The "closed continuum" of cause and effect is a modernist myth. The God who does not "intervene" from outside but is always present and active within the world, sometimes shockingly, may well have been thus active on this occasion.
It is all very well to get on one's high metaphysical horse and insist that God cannot behave like this, but we do not know that ahead of time. Nor will the high moral horse do any better insisting that God ought not to do things like this, because they send the wrong message about sexuality or because divine parentage gave Jesus an unfair start over the rest of us. Such positions produce a cartoon picture: the mouse draws itself up to its full height, puts its paws on its hips and gives the elephant a good dressing down.
You can read Wright's entire essay, "Suspending Scepticism: History and the Virgin Birth," here.