Short answer, no. Long answer. Christianity was unique in that the miraculous birth story that is told of Jesus was through a virgin. But other than that, a miraculous birth isn't all that uncommon. In The Gospel According to Judas, Jeffrey Archer and Francis Moloney argue that the conception of Jesus is just one more example of the sort of Greek myths that tell of a god producing an offspring with a woman on earth. Those stories require a physical union, so they aren't virginal in nature, but the over all concept was well known. For instance, we have the birth of Augustus, where the god Apollo is said to have impregnated Atia (Augustus's mother), making Augustus the son of a god. The work of Jeffery Archer and Francis Moloney has to be taken with a large grain of salt though, because while Moloney is a great scholar, Archer was writing a fictional story. But they do nail the Greek myth part.

I mention that work though because Gerald O'Collins uses it to launch an article titled The Virginal Conception and Its Meaning. O'Collins doesn't discredit the fact that there were a host of such myths going around about Greek and Roman figures, but he objects to the idea that Jews in Palestine would have known those stories and thus copied them. He points out that when the virginal birth is raised by outsiders, the argument is that Mary committed adultery and had a child. Celsus, a pagan author from the late second century, made the claim that Jesus's actual father was a soldier named Panthera, and that he had heard this from the Jews.

The birth of Jesus, from a virginal conception, would have actually appeared more outlandish to Jews than it probably would have to the Greco-Romans because the Greco-Romans already knew of figures who were said to have been born of a woman and a god. The woman being a virgin would have been a new spin, but the overall idea was already there.

But we also have to look at how the virginal birth came to be. Paul never speaks of it. He makes it appear as if Jesus had a natural birth, saying that he was born of a woman. That would have been the common phrasing. It isn't until Matthew and Luke that we get this virginal birth story. There have been some arguments as to the birth narratives being a later addition, but many scholars see them more as theological in nature. O'Collins runs that view down in his work, and one of the best sources on the topic, Raymond Brown's Birth of the Messiah also takes that view.

So what we can say on this point is that the virgin birth narratives are later, and they don't seem to be questioned all that much. When they are, it's not based on the idea that it couldn't happen, but instead that this was a case of adultery.

Just one more point. We learn from the Pauline epistles that the manner in which Gentiles were brought into the faith was that a missionary, such as Paul, would first go to local synagogues (or places Jews gathered) and preach there. Pamela Eisenbaum, in Paul was not a Christian, really breaks this down. The reason to go to the local synagogues, for someone like Paul who was only entrusted to preach to Gentiles, was because of a set of people called God-fearers. These are Gentiles who like the Jewish message, but don't fully convert (often they simply wouldn't get circumcised). These God-fearers were really a stepping stone to the larger Gentile population.

So it was a gradual spreading. And we can be somewhat certain that it is out of this that the virgin birth stories first begin forming. It's as the story is spreading that a theological tradition is created, giving Jesus a miraculous birth. This wouldn't have been strange to the Gentiles as they would have already been familiar with stories that had the same general ring to them.