There has been numerous debates on James being the real and younger brother of Jesus.
I think this can not be!

If we step away from the New Testament (NT), which is heavily edited by the Church anyway, we can find the apocryphal texts like Nag Hammadi.
There we find; The (Second) Apocalypse of James.

Here we read:
This is the discourse that James the Just spoke in Jerusalem, which Mareim, one of the priests, wrote. He had told it to Theuda, the father of the Just One, (...)
[www.gnosis.org]

Now, if we also take:
"Once when I was sitting deliberating, he opened the door. That one whom you hated and persecuted < <he's talking about Jesus here>> came in to me. He said to me, "Hail, my brother; my brother, hail." As I raised my face to stare at him, (my) mother <<James'mother that is>> said to me, "Do not be frightened, my son, because he said 'My brother' to you (sg.). For you (pl.) were nourished with this same milk. Because of this he calls me "My mother". For he is not a stranger to us. He is your step-brother [...]."

And next take Jesus'words to James : "Your father is not my father. But my father has become a father to you." from the same text

There is almost no other way than to determine that James is at best (!) Jesus half brother. Otherwise the first paragraph would not have mentioned Theuda as the father of James, but Joseph ?!

Kindest :)
Nephil