Louis H. Feldman, "Use, Authority and Exegesis of Mikra in the Writings of Josephus," Mikra: Text, Translation, Reading and Interpretation of the Hebrew Bible in Ancient Judaism and Early Christianity, ed. Martin Jan Mulder (Peabody: Hendrickson, 2004) 507.
The fact that Josephus boasts (Life 9) that, while a mere lad...of fourteen, the chief priest and the leading men of the great city of Jerusalem used to come to him constantly for information on particular laws shows that he regarded himself as eminently well qualified to comment on the legal code.
A professor of mine once tied what Josephus says in Life 9 to Luke 2:46-47, which describes the activity of the twelve-year-old Jesus: "After three days they found him in the temple, sitting among the teachers, listening to them and asking them questions. And all who heard him were amazed at his understanding and his answers" (NRSV).
I'm not sure how the professor believed the passages were connected. Did he think that Luke used Josephus' story? I doubt he thought that Josephus drew on Luke, since he was trying to argue that the scene of young Jesus in the temple was not historically accurate. Perhaps his contention was that Luke uses a common storyline about great people in antiquity: that they were prodigies in their youth.
Perhaps. I'm not versed enough in ancient literature to know if it has lots of stories about young prodigies. I wouldn't be surprised if it did. The thing about Josephus' account is that it's not just the story of a great man who was once a gifted child. It's Josephus' autobiography, in which he professes to narrate his own life experiences. Would Josephus draw on a literary motif to embellish his life-story? Did people make things up when they wrote autobiographies?
Maybe Josephus actually was gifted as a youngster and prominent people consulted his knowledge of the laws. There are prodigies even today, so it's not a stretch to believe that they existed back then as well. But Josephus may remember what happened to him incorrectly, exaggerating the importance of the men who came to see him. I don't know.
What Feldman discusses in this section is the issue of Josephus' knowledge of the law. Josephus tends to get things wrong in his books, and Feldman discusses whether Josephus has become less exact with age, or if his errors are deliberate, as part of an attempt to make Judaism look good to the Romans.