[Cronos]

And, in the Bible brother has shades of meaning because Aramaic and other Semitic languages do not differentiate between a blood brother/sister and a cousin or other

For example

1. MAtt 1:2 "Jacob the father of Judah and his brothers," for step-brothers with the same father but different mothers
2. acts 3:17 "17And now, brethren,"
3. Luke 10:29 "and who is my brother"
4. Matt 5:47
5. Matt 23:8
6. Rev 22:9

So, yes, brothers had a wider meaning then just blood brother. And no, the term "Irdu" is not used biblically.

The NT was written in Greek, ok -- not all, but let's take your argument for the sake of argument. Remember also that the words of Jesus were mostly Aramaic or Hebrew or maybe even GReek -- we've already shown that in SEmitic languages like Aramaic/hebrew there is no differntiating term between a blood brother and a cousin, let's examine the GReek ouch outos estin o tekton o uios Marias adelphos de Iakobou Iose kai Iouda kai Simonos

If the term is that the adelphoi have the same mother then it would be ho adelphos But that is not used. Without the article adelphos is non-specific and non-exclusive and can mean kinsmen, relatives

Furthermore, I give you two examples of why He didn't have blood brothers of the same mother

1. Why give John to look after Mary -- that would be quite "rude" (at the very least) to his other brothers, not something a Jew in those days would do
2. Why does Mary act surprised when the Angel tells her she will conceive?

He also had brothers, half brothers.

perhaps brothers from his father's earlier wife maybe, or more plausibly cousins.

Have you been to the Middle-East lately? A guy will call his cousin his brother. This is true of this clan society just as it was in the time of Christ.

More importantly, you have no proof that they were the children of Mary -- if they were, then why did Jesus tell John to take care of His mother? that's a classic affront if he had any brothers through Mary

[CharlesWayneCT]

I’m not quite as concerned with getting absolute proof that they were Jesus’ brothers. It seeems we need absolute proof that Mary had no children. Even if there was no mention of children, that wouldn’t prove she was otherwise childless, or a perpetual virgin.

Given that Joseph was her husband, and they lived as husband and wife for at least the 33 years up to Jesus’ death, I think someone needs to provide proof in the form of a positive statement from the Bible or historical records that Joseph was a virgin. Because the bible clearly indicates that husbands and wives are supposed to sleep together, and the bible doesn’t say Joseph had a concubine, another wife, or was an adulterer, so if Mary was a virgin, then Joseph was as well.

And THAT is so impossible to believe that you need proof for it — much more so than any incredulity about younger siblings giving counsel to an older sibling.

Heck, we aren’t even told that Joseph was given some special dispensation such that he could live his life without ever having sex.