1 sn Verse 12 is merely a transitional note in the narrative (although Capernaum does not lie on the direct route to Jerusalem from Cana). Nothing is mentioned in John’s Gospel at this point about anything Jesus said or did there (although later his teaching is mentioned, see 6:59). From the synoptics it is clear that Capernaum was a center of Jesus’ Galilean ministry and might even be called “his own town” (Matt 9:1). The royal official whose son Jesus healed (John 4:46-54) was from Capernaum. He may have heard Jesus speak there, or picked up the story about the miracle at Cana from one of Jesus’ disciples.
2 sn With respect to Jesus’ brothers, the so-called Helvidian view is to be preferred (named after Helvidius, a 4th-century theologian). This view holds that the most natural way to understand the phrase is as a reference to children of Joseph and Mary after the birth of Jesus. Other views are that of Epiphanius (they were children of Joseph by a former marriage) or Jerome (they were cousins). The tradition of Mary’s perpetual virginity appeared in the 2nd century and is difficult to explain (as J. H. Bernard, St. John [ICC], 1:85, points out) if some of her other children were prominent members of the early church (e.g., James of Jerusalem). But this is outweighed by the natural sense of the words.