Where can we find information about the Savior’s siblings? Thanks!
We answered this question in part previously. Did Jesus have siblings?
The Bible is the first, best, and only reliable source for information about Jesus’ siblings. Matthew 13:55-56 and Mark 6:3 tell us everything we know about the identity of Jesus’ siblings in the flesh. Jesus’ brothers were called James, Joseph (or Joses), Judas (or Jude), and Simon; he also had sisters, though these were not named.
The book of Mark mentions three men named James: James the son of Zebedee, James the son of Alphaeus, and James the brother of Jesus. The first two of these were apostles of the Lord. In his epistle to the Galatians, Paul mentioned that Jesus’ brother James was an apostle. Because of this, James the brother of Jesus is often associated with James the son of Alphaeus. Does this mean that Joseph, the husband of Mary, Jesus’ mother, was also named (perhaps surnamed) Alphaeus? Possibly. We simply don’t know.
Some Christian faith traditions maintain the “perpetual virginity” of Mary the mother of Jesus. To explain Jesus’ siblings, these traditions assume that the so-called brothers and sisters of the Lord were actually step-brothers and step-sisters, children of Joseph through a supposed first wife who died before Joseph married Mary. Latter-day Saints have no doctrinal reason to resort to such suppositions, so the most natural reading would make Jesus’ siblings his younger half-siblings, the sons and daughters of Mary and Joseph.
(As further implicit evidence of this idea, note that the last verses of Matthew 1 read: “Then Joseph being raised from sleep did as the angel of the Lord had bidden him, and took unto him his wife [Mary]: And knew her not till she had brought forth her firstborn son: and he called his name JESUS.” The verb “knew” here is a Hebrew idiom referring to sexual activity. The fact that Matthew specifies that Joseph “knew her not till [Jesus’ birth]” suggests that after the birth of the Lord, Joseph and Mary engaged in normal marital relations as husband and wife.)
The bottom line is that we haven’t been given many specifics of Jesus’ family situation. Our best and most reasoned guesses are ultimately just that—guesses. For us, Jesus’ most important familial relationships are those of premortal elder Brother chosen to work an infinite atonement for us, and through that atonement, Father of our reborn souls. All else is footnotes.