Joseph did not have children prior to Jesus. There is nothing in the bible that says that. Jesus clearly had brothers and sisters who were born to Joseph and Mary.
For those who are quoting the "early church fathers", are you saying you are a follower of them?
Or do you follow Christ and the bible? Because in the bible it names Jesus' brothers and Nowhere does it state that Mary was never to have sex with her husband. Do you think Joseph stayed married to a women who would never consumate the marriage? First of all, woman back then had a duty to consumate their marriage and the Catholic church even today would annul any marriage that was not cunsumated.
And on top of that are some trying to say Jospeh had affairs and fathered other children?
The whole idea of the perpetutal virgin is so that the Catholics can venerate Mary, this is a pagan belief and is not based on scripture at all. And is not a biblical teaching as your only mediator is Jesus and only HE can make intercession for your sins and grant your prayers.
Even if Martin Luther and some others had this wrong belief, it was merely based on traditions of the Catholic church and not the bible. And, frankly, they were wrong. Its as simple as that.
Christians are to be followers of Christ and obey his words regardless of what the churches say as these are man made institutions only and every single one of them has deviated from the bible and added thier own teachings, creeds and traditions to God's word.
And it is useless to go to a Catholic website or source to find out the origins of their teachings. Just like the WT will not give you information that shows their religion in a negative light. If anyone would like some information contrary to the Catholics claims which shows the origin of all the practices that are unique to them including "the perpetual virgin" here is a good book:
The Two Babylons - by Alexander Hislop- Chick Publications