If one only had the Scriptures, one might assume that what you say is true, which is,however, to ignore the incompleteness of the New Testament record and the antiquity of the notion that the brothers were the offspring of St. Joseph. The best example of that, of course, is the "proto-Gospel of St. James," which is generally dated to the 2nd century, which would make it as old as some parts of the New Testament canon. But we must look at how little is said about St. Joseph before we talk about a "normal" Hebrew marriage. As for dismissing the notion of "cousins," we must take into account the dynamics of a Semitic clan, where cousins are often as close as brothers and where first cousins often marry. Given that , as you say. the "family" was hostile to his mission--a stretch indeed if you try to include Mary, given what Matthew and Luke say about her--the Gospels deal with them only in passing. If we look at Paul as a source. you have to be especially careful, because he says nothing about the Virgin Birth. does not even mention Mary's name. Doubt that he and James ever had any heart-to-heart about life in the Bar-Joseph household.
Psalm 69:8-9
You'll find it in Psalm 68:9-10 in the "Douay-Rheims".
[An alien to the sons of my mother.]
Please then explain Mark 3:20-21, [Then Jesus entered a house, and again a crowd gathered, so that he and his disciples were not even able to eat. When his family heard about this, They went to take charge of him, for they said, "He is out of his mind".] In verse 31 [Then Jesus' mother and brothers arrived. Standing outside, they sent someone in to call him.]