[PugetSoundSoldier]

Genesis wasn’t written in Greek; it was translated into Greek.

Show me an original Greek writing, or something from the NT where the word “brother” means cousin or kin.

[kosta50]

Show me an original Greek writing, or something from the NT where the word “brother” means cousin or kin.

It's a custom to this day in the Mediterranean and Middle Eastern culutres to call first couisns and relatives "brothers" and "sisters."

The Hebrew word 'ach is defined as brother, brother of same parents, half-brother (same father) relative, kinship, same tribe, each to the other (reciprocal relationship), (fig.) of resemblance.

The word for sister is 'achowth, defined as sister, sister (same parents), half-sister (same father), relative, (metaph) of Israel's and Judah"s relationship, beloved bride, (fig.) of intimate connection, another

[kosta50]

Greek word for borther is adelphos, defined as a brother, whether born of the same two parents or only of the same father or mother, having the same national ancestor, belonging to the same people, or countryman, any fellow or man, a fellow believer, united to another by the bond of affection, an associate in employment or office

[annalex]

Show me an original Greek writing, or something from the NT where the word “brother” means cousin or kin.

First, I apologize, the OT reference was meant to be Gen 13:8. I do not see why only original Greek texts should matter. The fact is that both in Hebrew and Greek "brother" is sometimes used expansively. The Nazarene speaker who identified James and Joseph as "brothers" of Jesus was most likely using Aramaic, language close to Hebrew but not Greek. When the Greek author translated Genesis he chose to translate the Hebrew "akhim" as "adelphoi":

Genesis
	English: Douay-Rheims	Hebrew OT: WLC (Consonants Only)	Greek OT: LXX [A] Unaccented
	Genesis 13
8.	Abram therefore said to Lot: Let there be no quarrel, I beseech thee, between me and thee, and between my herdsmen and thy herdsmen: for we are brethren.	ויאמר אברם אל־לוט אל־נא תהי מריבה ביני וביניך ובין רעי ובין רעיך כי־אנשים אחים אנחנו׃	ειπεν δε αβραμ τω λωτ μη εστω μαχη ανα μεσον εμου και σου και ανα μεσον των ποιμενων μου και ανα μεσον των ποιμενων σου οτι ανθρωποι αδελφοι ημεις εσμεν	.8

But, of course, Lot was Abram's nephew, not brother as is clear from Gen. 11:27,31.

Here is, however, another expansive usage in the Greek new testament:

Matthew
	English: Douay-Rheims	Greek NT: Byzantine/Majority Text (2000)
	Matthew 13 [similar Mark 6:3]
55.	Is not this the carpenter's son? Is not his mother called Mary, and his brethren James, and Joseph, and Simon, and Jude:	ουχ ουτος εστιν ο του τεκτονος υιος ουχι η μητηρ αυτου λεγεται μαριαμ και οι αδελφοι αυτου ιακωβος και ιωσης και σιμων και ιουδας

Well, the same Evangelist identifies the mother of James and Joseph as another Mary in Matthew 27:56 and Mark 15:40.