>>While I understand the desire for Roman Catholic's to prove that Jesus had no biological brothers, I have never got to excited about it. I mean that it isn't something which salvation is hanging on.<<
No, but Protestant apologists keep bringing it up. And a model of perpetual virginity is very important to the Catholic priesthood.
It certainy strikes newspaper editors as important. Can anyone explain to me why an unconfirmed claim about an ossuary was scrawled all the way across every national newpaper of record? I couldn't believe when the scratches proved to be recent. That was the first thing I'd've looked for!
There is a division between Catholics and Greeks on the issue of Jesus' siblings. Greeks assert that the gospel's Greek language is perfect, and therefore assert both that Mary had no children ("THE son of you,") but that Jesus had brothers. Hence, they suppose Joseph had sons by a previous wife. This does fit ancient legends concerning the marriage of Joseph and Mary. (Legend is Joseph was an old man who was ashamed to take practically a mere child -- 13 years old! -- for his wife. Imagine his horror when every-one would've thought he couldn't even wait until their marriage to have relations with her! They must've thought he was a horny old lech!)
While the Catholic Church does not formally denounce this, Joseph is considered by Catholics and in Catholic prayers to be also "ever-virgin."