Son of Joseph

Was Jesus the son of Joseph?
While Joseph undoubtedly cared for Jesus as his son while Jesus grew from an infant to a man, Jesus is not the biological son of Joseph (see Birth of Jesus).

Who is asking,“Is this not Jesus, the son of Joseph, whose father and mother we know” (John 6:42)?
“The Jews” (John 6:41) refer to Jewish leaders and may include those in the crowd that had chased after Jesus to Capernaum after His feeding miracle the day before, the Jewish leaders from Capernaum, and/or the Jewish leaders from Nazareth, where Joseph, Mary and Jesus lived until Jesus “began His ministry at about thirty years of age” (Luke 3:23).

How did “the Jews” know Joseph and his wife Mary?
Mary came to Capernaum with Jesus after His ministry began: “He went down to Capernaum, He and His mother and His brothers and His disciples” (John 2:12), so the Jews in Capernaum would have known her. Since Joseph isn't mentioned in the group that arrived in Capernaum (see Jesus' Brothers), he most likely wasn't with them, so this crowd likely also included Jews from Nazareth, which is only about 20 miles (52 kilometers) away, in Capernaum to oppose Jesus. After all, they had tried but failed to kill Jesus in Nazareth: “And having risen up, they thrust Him out of the town and led Him to the brow of the hill on which their town had been built, that they might throw Him down headlong. But passing through the midst of them, He went His way” (Luke 4:28-30).

Was Joseph still alive at this time?
He could have been and simply not mentioned again during Jesus' ministry, or he could have died but remembered by those who had known him.

Do the Jews understand Jesus' spiritual message about the will of the Father?
No, they are still stuck on physical “bread” (John 6:41) and see Jesus only the son of a (former) acquaintance.

Does Jesus plead with them to see Him spiritually?
He chastises them instead.