Imagine Jesus the bastard child of Mary taken in by the carpenter as his own son. The carpenter Joseph raises Jesus as his own and presumably trains him to be a carpenter also. Joseph disappears from the record, probably due to early death, so that we never hear of him again in the Gospels in the active sense, beyond the time when Jesus at the age of twelve tarried in the temple according to Luke. Thus Jesus no doubt became the man of the family and its material provider from that point on, which would explain in part why the spiritually precocious child had to wait so long to begin his public ministry as a teacher with pupils. He had a personal obligation of support for his family, which also included training his younger brothers in the trade to take over for him when the time was right.
Jesus turned his back on all this, that is, he repented of his former life, when he left them all and submitted to the baptism of repentance, the baptism of John. In doing so Jesus was demonstrating that he himself was willing to pay the price of discipleship, personal poverty, which he demanded his followers to pay also. "No man can be my disciple who does not say goodbye to everything that he owns."
We can well imagine how this went over with his own family, which found it difficult to accept even if it never caused them to shun him as he now seemed to shun them. The famous scene in Mark 3 where Jesus fails to recognize them as his true mother, sisters and brothers no doubt was confirmation to them that he was indeed "beside himself". You can almost hear some of them saying, "Brother Jesus has gone off the deep end and started a cult!"
But to others from Jesus' hometown not simply the failure to meet his social obligations but his rejection of those obligations in principle was a scandal causing them to be indignant at him, despite his reputation for "success" as a prophet and wonder worker, and now they felt alienated from him. "What if everyone did what he did? How would anyone survive? Those unwilling to work will not get to eat! If any one does not provide for his relatives, and especially for his own family, he has disowned the faith and is worse than an unbeliever!"
