That's the teaching of the RCC but it is not based on the Bible. I've provided you with the biblical evidence at #1599. Be honest: Jesus can't have any half brothers ans sisters without the sexual intercourse of Joseph & Mary. If Mary didn't give birth to these extra children, did she have extra-marital sex with somebody.
First Jesus Christ alone founded the one true church Matt 16:18 and said Lk 10:16 it teaches thee faith eph 4:5 Jude 1:3
the brothers here could be children of Joseph from a prior marriage but more l ok likley cousins,
Brothers and sisters of Jesus?
They are not the children of Mary!
Is 7:14 a virgin shall conceive and bear a son!
(One son, singular)
James is the son of zebedee, and the other James is the son of Alpheus not Joseph!
Matt 10:2-3
In Hebrew culture any close relative can be called brother or sister, lot was called Abraham’s brother but was his nephew.
Gen 12:5 and Abram took Sarai his wife, and Lot his brother's son..
Gen 13:8 And Abram said unto Lot, Let there be no strife, I pray thee, between me and thee, and between my herdsmen and thy herdsmen; for we are Brothers.
The 12 sons of Jacob are brothers but all are not the children of Leah and all are not the children of Rachel! They may be brothers and sisters but they are simply not the children of Blessed Mary ever Virgin mother of God!
Jose’s, Simon Salome are children of another Mary!
Mk 15:40 There were also women looking on afar off: among whom was Mary Magdalene, and Mary the mother of James the less and of Joses, and Salome;