Did Jesus Have Brothers?

The wide meaning of "brother"

"Brothers" and "sisters" of the Lord appear about ten times (Matthew 12:46; 13:55; Mark 3:31-34; 6:3; Luke 8:19-20; John 2:12; 7:3, 5, 10; Acts 1:14; 1 Corinthians 9:5). But "brother" (adelphos) in the Bible is not limited to full or half brothers. It can mean any male relative who is neither ancestor nor descendant, kinsmen, in-laws, and even friends or allies (2 Samuel 1:26; Amos 1:9).

Lot, Abraham's nephew (Genesis 11:26-28), is called his brother (Genesis 14:14).
Jacob is called the brother of his uncle Laban (Genesis 29:15).
Eleazar's daughters married their "brethren," actually their cousins (1 Chronicles 23:21-22).
"Brethren" also means kinsmen (Deuteronomy 23:7; Nehemiah 5:7; Jeremiah 34:9), as with the forty-two "brethren" of King Azariah (2 Kings 10:13-14).

No word for cousin

Hebrew and Aramaic had no word for "cousin," so Jews often said "brother." The Septuagint translated this with adelphos, even for true cousins, though Greek had a word for cousin (anepsios). The New Testament writers did the same.

The context

When Gabriel announced she would conceive, Mary asked how, since she had no relations with a man (Luke 1:34). The Fathers took this to mean she had vowed lifelong virginity; otherwise the question makes no sense.
The finding in the Temple at age twelve suggests Jesus was the only child (Luke 2:41-51).
Nazareth called him "the son of Mary" (Mark 6:3). No one else is ever called Mary's son, not even his "brethren."
His "brethren" advised him to go to Judea (John 7:3-4). In that culture younger brothers did not advise older ones, so they were older; but Jesus was Mary's firstborn (Luke 2:7).
Dying, Jesus entrusted his mother to John (John 19:26-27), which would make no sense if James, Joseph, Simon and Jude were her sons.

"Until" and "firstborn"

Matthew 1:25 says Joseph did not know Mary "until" she bore her son. In the Bible "until" means only that something did not happen up to a point, not that it happened afterward: Michal had no children "until" her death (2 Samuel 6:23), and no one knew Moses' grave "until this present day" (Deuteronomy 34:6). The New American Bible renders it: he had no relations with her at any time before she bore a son. "Firstborn" meant the child who opened the womb (Exodus 13:2; Numbers 3:12), even if there were no others.

Mary's perpetual virginity

Fundamentalists call a celibate marriage unnatural. It was unusual, but this family was set apart to raise the Son of God. When Helvidius around 380 first claimed the brethren were Mary's children, Jerome answered with Scripture and with Ignatius, Polycarp, Irenaeus and Justin Martyr.

Who were the brethren?

Before Jerome, the standard view was that they were Joseph's sons by a first marriage, as the Protoevangelium of James records, which also explains their older brothers' attitude. Today most hold they were cousins. James the younger's mother was Mary (Matthew 27:56; Mark 15:40), the wife of Clopas (John 19:25). James is elsewhere called son of Alphaeus (Matthew 10:3), but Alphaeus and Clopas can render the same Aramaic name, or Alphaeus took a Greek name as Saul took "Paul." Hegesippus says Clopas was Joseph's brother, making James Jesus' cousin. Whatever their exact status, the Bible shows they were not Mary's children.