I figure all that stuff was added later by somebody trying to reconcile the OT with the new Christian Church. I think they were very concerned to add to Jesus' standing or credibility or something by making him the literal son of God. Jews never really expected an actual virgin to give birth to the messiah. Their young girls are not all anxiously awaiting God to overshadow them or something. But the Christian church seemed to get caught up in a lot of other things happening religiously in the region at the time, not to mention they all seemed to go wacky about sex in general. Read up on the early martyrs-it was nuts. The early church fathers- many seemed to have 'issues' with sexuality. I don't know exactly what brought on the religious mania against sex, but clearly they had one. Except for the looneys who took it in the other direction.
You know-people have been screwed up for millenia!