Did Jesus have brothers? There is one instance where the Gospels say your brothers are outside.
Answer: The New Testament does mention brothers and sisters of Jesus: Mt 12:46 ff.; 13-55ff.; John 2:12; 73:5-10.; 20:17(?); Acts 1:14; 1Cor 9:5; Gal 1:19. Four brothers are mentioned by name: Jacob (the younger, Mk 15:40), Joseph or Joses (The spelling is not always the same in the hand written texts), Simon and Judas (Mt 13:55; Mk 6:3). There is no record of the names of the sisters.
(I) When answering this often recurring question it is important to make a clear distinction between the probably and the unlikely. It is certain that these people are not brothers and sisters of Jesus in accordance with today’s meaning of the words, i.e. they were definitely not children of Mary, but distant relatives, e.g. cousins of Jesus. In the Greek language, in which these reports were written, the words brother and sister usually have the same meaning as we understand today. However, in this case we are permitted to consider the Green expressions as a literal translation of an Aramaic equivalent, which was used by the early Christian community in Palestine as an expression for a certain group of people related to Jesus; Brothers of the Lord or Jesus brothers was apparently a known expression, cf Acts 1:14; 1 Cor 9:5. As can also be seen in the OT (Gen 13:8 – Lot is Abrahams brother; 14:14-16; 29:15), the Aramaic (and Hebrew) use of the word differs from ours in this respect. In those languages, the word brother (Hebr. ۥākh) also includes distant relatives such as nephews and cousins, because they do not have terms describing those relations more precisely. For example, the expression the brothers was used in order to avoid descriptions such as the sons of the uncle and the suns of the mothers sister) (Lagrange). That the authors of the NT knew about the multiple meanings of the word adelfós can be seen in John 1:41, where Simon is described as the true brother of Andrew.
(II) This fact makes it appear possible that the brothers of Jesus are distant relatives and not genuine brothers. That this is truly the case will be shown in the following.
(A) The four named brothers of Jesus Mk 6:3 (Mt 13:55) are sons of another mother than the mother of Jesus; the first two, Jacob and Joseph (Joses), are mentioned again later in Mark as well as in Matthew in the story of Jesus crucifixion, and are there named as sons of a different Mary from the mother of Jesus (Mt 27:56; Mk 15:40). It is not entirely impossible that this report refers to other persons. However, when a writer mentions two brothers by name and when he later repeats those names in a short piece of writing without any further explanation, it has to be assumed that he refers to the same two people. This also gives rise to the fact that the other two (Simon and Judas), who appear much later and much further distanced from Jesus, are also not brothers in our sense of the word; It is probably that these persons are cousins of a different origin, especially since they are not mentioned in Mt 27:56 ; Mk 15:40.
(B) This conclusion is confirmed in that according to the Gospels Jesus is the only son of Mary and the only child of the Holy family. At the time of Jesus birth Mary was a virgin (Mt 1:23; Lk 1:27) and intended to remain a virgin ( Lk 1:34).; All signs point to the fact that at the age of twelve Jesus is still the only son of Mary (Lk 2:41-52); Nowhere are the brothers of Jesus (who first appear during the time of his public ministry), called Sons of Mary and or Joseph; On the cross Jesus entrusted his mother to John, one of his disciples (John 19:26), a fact that only truly makes sense if Mary had no other children but Jesus.
(C) From the verses quoted in point (B) we can also deduct with a strong probability that the brothers of Jesus were not children of Joseph from a previous marriage, as for example the proto-gospel Jacobi, Origines and Ambrosiaster (Migne Latinus 17,344f) believed. Just precisely what the relationship of Jesus and his brothers was cannot be proved with final certainty; This fact, however, does not change the first, negative part of the evidence. Eusebius (Hist. Eccl. IV, 22:4) cites a quote from Hegesippus, which is said to show that Simon and Judas are sons of Cleophas (cf. John 19:25). This Cleophas is an uncle of Jesus, i.e. a brother of St Joseph. Their mother would therefore be Mary of Cleophas, who stood beneath Jesus cross. The mother of Jacob and Joseph (Joses) would be the sister of Jesus mother mentioned by John, whom Mk 15:40 calls Mary, and who can therefore not have been a blood sister of the holy virgin. Her father would have been Alphaeus (Mt 10:3), provided it is possible to equate Jacob, brotherof the Lord with the disciple Jacob Alphaei. Not all exegetes accept this, however. In this explanation John 19:25 would mention four people. Others would like to equate Alphaeus with Cleophas and therefore see only three people named in John 19:25. According to this view, the four brothers of the Lord would be four blood brothers, and beneath the cross there would only have been one other Mary next to Mary the mother of Jesus and Mary Magdalene. This other Mary would then have been the wife of Cleophas (Alphaeus), the mother of the four brothers of the Lord and sister of Mary, the mother of Jesus (John 19:25). (slightly abbreviated text by W. Grossouw, art. “Brüder Jesu” in H. Haag (ed.), Bibel –Lexikon. Einsiedeln/Zürich/Köln, 1956), p. 262f.