This discussion (regarding the perpetual Virginity of the Holy Virgin, Jesus's Bretheren) has been going on for quite some time.
In this discussion St. Jerome (we've all heard of him) has a talk with one "Helvidius" regarding the matter.
Here is a link to the site and you can read it for yourself if you so desire.
http://www.newadvent.org/fathers/3007.htm
Enjoy. Not only does St. Jerome (the saint who translated the Bible) discuss the perpetual Virginity of Mary, he also discusses the topic of "Jesus's Brethren" and how Virginity is preferable to the/and in the married state.