Mark 6 :3 Isn't this the carpenter? Isn't this Mary's son and the brother of James, Joseph, Judas and Simon? Aren't his sisters here with us? And they took offense at him.
James and Joses (also translated Joseph, see
footnote) are not Jesus' brothers if we compare passages. Despite that, they are called His brothers in Matthew 13:55.
It is apparent if you compare
Mt. 13:55 with
Mark 6:3,
Mark 15:40 and
John 19:25, you will see that James and Joseph are quite likely the sons of Mary the wife of Clopas.
A closer look:
Here are two accounts of the Crucifixion scene:
Mark 15:40 Some women were watching from a distance. Among them were Mary Magdalene, Mary the mother of James the younger and of Joses, and Salome.
John 19:25 Near the cross of Jesus stood his mother, his mother's sister, Mary the wife of Clopas, and Mary Magdalene.
You have 3 Marys at the Crucifixion. Mark doesn't mention Mary the mother of Jesus at that point, but tells us that a Mary who is the mother of James and Joses is there. These men were called the "brothers" of Jesus in Mk 6:3 and elsewhere. So which Mary are they the sons of? Mark again refers to this woman as "Mary the mother of Joses" in Mark 15:47.
If one wants to insist that Joses is Jesus' brother, one has to argue in favor of 2 minimally likely scenarios, and at best admit Scripture is silent. The first argument would be that Mark refers to Jesus' mother as Mary the mother of Joses as the way to identify the woman who gave birth to the Savior. Or second, one has to say at the same time there were two women at the Cross named Mary with sons named James and Joses---and also claim that even though there were 2 women with sons named James and Joses, Mark apparently didn't think it would be confusing to identify only one of them as such!
Plus the repeated legitimate Greek of adelphos that others have posted.