I did have a roommate. But you are imputing a roommate relationship into Jesus's relationship with His disciples. The gospels do not warrant that, -- there is always a certaion distance felt between them, as is proper between teacher and pupil.
Moreover, you are imputing the erasure of privacy that is characteristic of the modern West, into relationships of a different era, even between peers. I am not convinced that even fellow pupils in 1 Century Israel were at ease discussing the sex lives of their parents. It is hard for me to imagine that Jesus would sort out to his apostles the who is who of his large (large enough for Mary to lose him for days among various siblings) family, even more so when he several times made an effort to explain that these familial ties are less important than spiritual kinship.
There is one aspect where being a biological brother would have mattered, an that is in taking care of the aging mother. But interestingly, it was John, not James, who Jesus selected for that role.
"But interestingly, it was John, not James, who Jesus selected for that role."
This is one of the most compelling points in Scripture that confirms that Mary had no other children besides Jesus. According to the tradition of the Church, St. James was probably no younger than the Virgin Mary herself, and would not have been, even as a step-son, necessarily a good choice for entrusting his mother. The fact that St. James was chosen to be the bishop of Jerusalem was probably at least in part because he was the oldest of the close followers of Christ, just as St. Peter's position as the chief of the Apostles was probably in no small part because he was the oldest of the 12.
As the youngest of the 12, St. John would be the logical choice to care for Mary. If the Virgin had other, younger children, they would have been the logical choice.
I would also point out that the same logic that has been used earlier in this thread, namely that "Matthew should have known" about the sibling issue one way or another -- this same logic should apply to the whole of Church tradition. I am unaware of any statement anywhere in the ancient writings of the Church that point to anything besides Mary remaining a virgin after giving birth to Christ.
One would expect that if the Apostles knew that Christ had blood (half) brothers, this inner tradition of the Church would have been strong enough that the tradition of Mary being a perpetual virgin would never have arisen.
At the very least, we would expect some record of polemics from the early centuries where this was contested -- by heretics, if no one else -- if there was a clear tradition that Christ had blood (half) brothers. There is no such polemical debate recorded, as far as I know.
There is of course also the question of why, from the earliest times of post New Testament Christian literature, she is referred to as "the Virgin Mary." If she had gone on to have sexual relations and bearing multiple other children, I find it hard to see why she would have received that title in the Church. We would speak of her as having been a virgin at the time of conceiving Christ, but she wouldn't have been given the title of Virgin.
Forgive me if I've repeated anything written by others.
That's how you want to put it? That sounds pretty desperate to me. I'm talking about casual conversation about one's family. Jesus certainly could be formal, but He also just as certainly showed a personal side. You deny that He showed any of it to even His own disciples. All I can do is realize that your hands are tied.
There is one aspect where being a biological brother would have mattered, an that is in taking care of the aging mother. But interestingly, it was John, not James, who Jesus selected for that role.
Yeah, well maybe there's a pretty good reason why Jesus didn't ask James. Perhaps because HE WASN'T THERE. John is the only disciple that is recorded as having actually witnessed the crucifixion. John had the greatest inner strength, he was the one whom Jesus loved, he was the one Jesus trusted to take care of Mary. There is nothing strange about that.