Because the Bible clearly says that Jesus had brothers, as I have shown you many times. Why won't you believe the Bible? What compels you to post all kinds of nonsense?
There is no indication anywhere in the Bible that they are children of Joseph from a prior marriage, nor does it say anywhere that they are cousins.
What disturbs me is your constant need to distort the clear teachings of the Bible to conform to your own false ideas (or those taught you by your priest). It is heresy of the highest order! => the Bible is God's word in written form <= By deliberately twisting the words of the Bible you are going against God!!!
If I were you I would immediately drop to my knees and beg God's forgiveness for your deliberate twisting of His word!!!
The first recorded argument was between St. Jerome and another fourth-century theologian, Helvidius, who had written that after the virgin birth of Jesus, Mary had other children with her husband, Joseph. St. Jerome disagreed, indicating that by the fourth century at least some of the church community believed that Mary had stayed a virgin for the rest of her life. These children of Mary, Jerome said, were from Mary of Clopas, Jesus’ aunt and his mother’s sister, making them cousins. He claimed that the Greek word adelphios could refer to cousins, not just biological siblings.