The only account Luke chose to go into detail about from Jesus' childhood was when He was twelve years old. By that point he would have been old enough to develop relationships with peers and adults, and there would have been a number of witnesses from Galilee and Jerusalem Luke could interview about it.
41 Now his parents went to Jerusalem every year at the Feast of the Passover. 42 And when he was twelve years old, they went up according to custom. 43 And when the feast was ended, as they were returning, the boy Jesus stayed behind in Jerusalem. His parents did not know it, 44 but supposing him to be in the group they went a day's journey, but then they began to search for him among their relatives and acquaintances, 45 and when they did not find him, they returned to Jerusalem, searching for him. 46 After three days they found him in the temple, sitting among the teachers, listening to them and asking them questions. 47 And all who heard him were amazed at his understanding and his answers. 48 And when his parents saw him, they were astonished. And his mother said to him, “Son, why have you treated us so? Behold, your father and I have been searching for you in great distress.” 49 And he said to them, “Why were you looking for me? Did you not know that I must be in my Father's house?” 50 And they did not understand the saying that he spoke to them. 51 And he went down with them and came to Nazareth and was submissive to them. And his mother treasured up all these things in her heart.
We find recorded here the devotion of both Jesus and His parents to please God. Just as they had taken Him as an infant to the temple, they continued on to observe the Passover and train their son in the faith. Jesus was also devoted to obeying His Father, and as a part of that, He was devoted to obeying His earthly parents, in obedience to the fifth commandment. As we all know, keeping a balance in relationship responsibilities is never easy, especially if we believe there is a conflict between obeying God and obeying parents. Jesus handles this masterfully, and respectfully of both, and Mary knows it. Luke has chosen the one extreme event which would reveal any sin on Jesus' part which could be witnessed to by numerous people, and found no sin. Jesus has a lot to teach us about how to handle interpersonal relationships.