For those God foreknew he also predestined to be conformed to the image of his Son, that he might be the firstborn among many brothers and sisters.
Very few have noted that Jesus is declared the firstborn among spiritual brothers.
Not coincidentially, Jesus continues to be the firstborn of the brothers even when the brothers are mere carnal brothers:
...and she gave birth to her firstborn, a son.
(Luke 2:7)
This is very the last nail on the coffin of the myth of 'carnal brothers of Jesus'.