Saint Jude was one of the Twelve Apostles. He was the son of Joseph and Salome and the brother of James, the brother of the Lord. With Salome, the daughter of Angeja the son of Varahina, the brother of Zacharias, Joseph the carpenter had four sons: James, Hosea, Simon and Jude. This Jude is sometimes called: "Jude, the brother of James" because of his more famous brother (St. Luke 6:16 Acts 1:14).
St. Jude begins his epistle in this manner: "Jude, the servant of Jesus Christ and the brother of James" (St. Jude 1:1). Even though he could be called the brother of the Lord as much as James, he did not do this out of humility and shame for, in the beginning, he did not believe Christ the Lord. When the elder Joseph, before his death, wanted to leave a portion of his estate to Jesus as well as to his other children, all of them protested this, even Jude, only James voluntarily set aside a share of his portion and intended it for Jesus.
From the Prologue.