Helen Bond notes:

‘The Synoptics record a story in which Jesus’ mother and siblings hear that he is ‘beside himself’ and come to take him home, only to be rebuffed by Jesus (Mk 3:21, 31–4 and pars.).

‘Later on, Jesus’ preaching in the synagogue at Nazareth strikes his hearers as arrogant and presumptuous, prompting him to remark that ‘a prophet never lacks honour except in his home town, among his own relations and his own family’ (Mk 6:1–6 and Mt 13:53–58; in Luke’s dramatic scene the townspeople even try to kill him, Lk 4:16–30).

‘John, too, notes that Jesus’ brothers had no faith in him and urged him to take his ministry to Judaea (Jn 7:1–5).

‘The family tension which stands behind all of these scenes is doubtless authentic.

‘Reasons for these strained relations are not difficult to imagine.

‘Like many people at the time, Jesus belonged to a large family, with four brothers and a number of sisters (Mk 6:3, Mt 13:55). Perhaps the family initially felt obliged to offer hospitality to Jesus and his companions, hospitality which would quickly have drained their resources.

‘And if Joseph was now dead (as the reference to his mother alone in Mk 6:3 suggests), Mary may well have expected Jesus (as the eldest son?) to take charge of the family, to arrange his sisters’ marriages, and to provide for them financially.

‘Perhaps his brothers saw Jesus’ lifestyle as an abdication of his responsibilities, a desertion which increased the pressure on themselves and their own families.

‘There is evidence of a reconciliation later on—two evangelists put Mary in Jerusalem at the end of Jesus’ ministry and his brother James emerged as leader of the Jerusalem church following a vision of the resurrected Jesus.

‘At the earliest stages, though, the family seem to have been unsupportive, leading Jesus both to redefine his ‘true family’ as those who accepted his message (Mk 3:31–4 and pars.; Lk 11:27–8), and to make his centre of operations elsewhere.’

The Historical Jesus: a Guide for the Perplexed, ch. 9 (paragraphing added)