Ummm...no. And that is a huge leap in order to support the Catholic teaching of the perpetual virginity. I really don’t get why Catholics hold on to that doctrine so tightly, it isn’t biblical and frankly Spiritual marriage isn’t Godly.
Why is it so hard to grasp that a married couple (Joseph and Mary) had sex and children?
BTW, considering the issues with liberals in the Catholic church, your tagline is silly. I know plenty of non-Catholic Christians with higher standards than almost every single Catholic I know.
Why is it so hard to grasp that we don't want to believe an innovation not taught in Scripture? Show me the scripture that identifies anyone other than Jesus as a son or daughter of Mary. For that matter, show me the scripture that identifies anyone other than Jesus as a son or daughter of Joseph. You can't; they don't exist.
In fact, in the case of James, identified as "a brother of Jesus," we know exactly who his father was: Alphaeus. (Mt 10:3) As far as Judas (aka "Thaddeus", "Judas, not the Iscariot"), also identified as a "brother of Jesus," we know who his father is as well: James (Acts 1:13). Joses (another "brother") was at least the half-brother and probably the full brother of James; their mother was a woman named Mary (Mt 27:56) who was not the mother of the Lord, or she would have been identified as such.
You "don't get" why Catholics hold on to that doctrine so tightly? Because it's true, and it's absolutely consistent with Scripture and in fact required by it. I "don't get" why you seem hung up on getting Catholics to reject a doctrine that was held by all the Reformers (look it up!) and is held by all Christians today except for some Protestants.