Did James and John already know Jesus before he called them to be his disciples?
Matthew 4:21–22 (ESV)
21And going on from there he saw two other brothers, James the son of Zebedee and John his brother, in the boat with Zebedee their father, mending their nets, and he called them.
Yes, these two brothers were cousins of Jesus since their mothers were sisters (see, for example John 19:25).1
21 And going on from there he saw two other brothers, James the son of Zebedee and John his brother, in the boat with Zebedee their father, mending their nets, and he called them.