The evangelist Luke wrote of a biological relationship between the mothers of Jesus and John the Baptist. Reportedly, the Angel Gabriel told Mary, “Your relative Elizabeth in her old age has also conceived a son.” (Luke 1:36).
The original Greek text does not tell us exactly how they were related, but common tradition has held that because their mothers were related, Jesus and John must have been cousins. After this detail, however, nothing else in our Bible mentions any interactions between the two during their childhoods. Indeed, the description of Jesus’ baptism by John the Baptist suggests that might have been their first meeting, which could then explain John’s question about Jesus’ true identity (see Luke 7:18-23).
One possible explanation for this seeming lack of relationship during their boyhood years is Luke’s detail that John “was in the wilderness until the day he appeared publicly to Israel” (Luke 1:80). The apocryphal “Infancy Gospel of James,” written perhaps in the mid-second century, mentions that John’s mother Elizabeth fled with him to the hill country to avoid Herod’s slaughter of the innocent boys born around the time of Jesus.