Can we trust the birth narratives of Jesus found in the Gospels?

Q: Many people assume that the birth narratives of Jesus found in the Gospels are fictional. Do you think they’re trustworthy? 

In order to answer this question, it is useful to compare the Gospels with other historical documents. As an ancient historian, I study texts in which most of the incidents that we know about are recorded only once. This is the case in the works of Tacitus or Suetonius, or any of the other great ancient writers. Almost all of the texts from the ancient world exist as only one or two mediaeval manuscripts. The work of Lucretius, the great epicurean poet from the first century BC, was lost completely until a singular manuscript was discovered in 1417 by Poggio Bracciolini. That means that epicurean studies were revived with just one manuscript! Even Josephus, the great Jewish historian, often recorded historic events only once.