When Jesus' body was twelve years old, He demonstrated His wisdom.
Mary and Joseph had been with Him in Jerusalem for the Passover, Luke 2:41-50.
They couldn't find Him when they were on their way home to Nazareth, "After three days they found Him in the temple" hearing and asking questions of the doctors, "And all that heard Him were astonished at His understanding and answers."
His body was only twelve years old, but His mind was well developed beyond His years.