What is the usual sense that religious things are taught? Through a Rabbi and disciple model. A young man that thinks he may have an aptitude for a particular Rabbi’s teaching goes to the Rabbi and ask to be considered to be a disciple. It was a great honor for parents especially the father for a son to be accepted.
The Rabbi asks questions of the potential disciples not to see how much he knows but to see if he really does get it: to see if the young boy really might be able to not just learn the facts but to live out the life of the Rabbi. The Rabbit is seeking to reproduce his life in the disciple. After many years of living and serving, maybe one day the disciple might be able to have some authority to do some of the teaching. Maybe when he was about thirty (How was Jesus when he started his ministry? Thirty) the disciple might actually be able to consider his own disciples.
Now the things that the Rabbi instilled in his disciples were the things that were instilled in him when he was a disciple. Nothing new was usually added unless there came an exceptional candidate that might actually have authority to add to the teaching or even create something new. But this happened once in a lifetime, maybe…
Jesus has already repeated this idea in chapter 10:24-25 when he said, “A student is not above his teacher, nor a servant above his master. It is enough for the student to be like his teacher, and the servant like his master.” The whole goal of the student was to be like his teacher.
Yet, Jesus had no Rabbi. He was a carpenter’s son. We don’t know exactly why Jesus was not given to a Rabbi. Probably for economic reasons. Tradition has it that Joseph died when Jesus was young. Perhaps Joseph was sick and Jesus just needed to help provide for the family.
Regardless, Jesus had no Rabbi.