Though Peter was married, it is doubtful that Mark (Marcus) was Peter’s "biological" son. We learn in Acts 12:12 that Mark’s mother was Mary and that her house was in Jerusalem. (Peter was from Galilee.) Also, Paul describes Mark as Barnabas’ cousin, not as Peter’s son. The word “son,” has often suggested affection and a spiritual relationship. Mark may have become a Christian under Peter’s ministry.