James was one of Jesus’ brothers (Mark 6:3) and this means that, if Jude was the brother of this same James, then he was also one of Jesus’ brothers. Despite this fact, however, like James (James 1:1), he does not emphasize his being Jesus’ brother because he prefers to see himself as a servant of Christ and does not want to suggest that he has more importance in the church on account of family ties.1
1 Jude, a servant of Jesus Christ and brother of James, To those who are called, beloved in God the Father and kept for Jesus Christ: