Catholic theology is much more poetic, much more cognizant of symbolism and literary biblical metaphors and allusions than Protestant theology. That is just a general observation of course, but to bring it back to Jesus is to bring it back to biography and history and what can be said for sure about who Jesus the man is. It is a "just the fact, ma'am" no nonsense attitude, like a hard nosed reporter wanting to cut to the chase.
And this is no doubt a part of the Christian tradition too, that goes back to the fights recorded in the New Testament against the Gnostics, and their own attempts to metamorphize Jesus into an ephemeral spirit, not of this world, not a man of flesh and bones that could be pinned to a cross like a butterfly on some scientists display, but a symbol of a man of a substance that is more apparent than real in this illusory world of pain and suffering and the crudity of meat and iron.
This of course is of the Catholic worldview too. Christ is a biography and a historic figure, and so too is his mother Mary.
Jesus is also a type. He says as much when he meets the two disciples along the road to Emmaus, post Resurrection, and explains to them how all of Scripture is fulfilled in him.
He is Moses, rescued from the slaughter of the innocents of Herod, then Pharoah. He is Isaac marching up the road to Golgatha dutifully following the word of his father, carrying the sticks for the fire of sacrifice. He is the ram caught in the brambles, his own skull ringed with those very thorns. He is Elisha to the Elijah of John the Baptist, seven times the miracles of the greatest prophet to date.
Very early on too, there began a theology of Mary based on these very allusions. This is Catholic theology. Mary as the Woman in Revelation, Queen of Heaven, Israel even, her head ringed with the halo of the twelve stars of Israel.
This is what her ever-virginity is based in, and biography has played very little role in the development of that theology. If Israel, then Jerusalem, portrayed in the Old Testament so often as a sexually fallen woman.
But if wanton before the Resurrection, Ever Virgin cloaked in the white garb washed by the blood of the lamb, Beloved Jerusalem, bride of the Father, and pure and virginal and sinless as is all of the creation that has been redeemed by our Savior.
EV is not biography; it was never meant to be. People who talk about Mary as the East Gate, and the Ark and the Woman of Revelation must understand all of this already. This is the language of symbol, and or metaphor, and of allegory. It is the language of archetype and of Spirit.
Some Catholic traditions speak of people referenced as brothers and sisters of Christ as step-brothers; other traditions reference them as cousins. It is therefore historically indeterminate just who these people are. Protestant explanations are as valid as any other when it comes to that.
For Catholics PV is de fide. The question of what PV implies however may vary considerably, just as it always has. St Jerome drew different conclusions than fathers of the east, and our theologies reflect our own understandings as the Holy Spirit continues to develop our religious consciousness of what is pure and virginal and sinless in our own lives, and in the lives of the women that we admire.