1. Scripture Passages That Say That Jesus Had Brothers and Sisters
Mark 6:3
Is not this the carpenter, the son of Mary, the brother of James (Yakoub) and Joseph (Yosei) and Judas (Yehudah) and Simon (Shimon) ?
Matthew 13:55-56
Is not this the carpenter’s son, whose mother is called Mary, and his brethren James and Joseph and Simon and Judas? And do not his sisters, all of them, live near us?
These passages from scripture tell us that Jesus had four brothers, Jesus also had sisters. Paul tells us that, at the Council of Jerusalem, James, the brother of the Lord, was present. This James was not James the Greater who was clearly identified as the brother of the Apostle John. He was also probably not James the Lesser though there is some debate about that. So how can that be true if Mary was considered ever-virgin (aeiparthenos in Greek). There are two explanations that were put forth

2. Jesus’ Brothers Were Actually His Cousins
This explanation states the fact that neither Hebrew nor Aramaic had a word for cousin (many references in the OT). While Greek, the language of the NT, does have a word for cousin (anepsios), the NT writers were translating Aramaic expressions into Greek in a literal, word-for-word fashion
(e.g. In Gen and 14.14, both the Masoretic Hebrew text and the Greek Septuagint use the word “brother” to describe Abraham’s relationship with Lot who was, in fact, Abraham’s nephew)
Matthew (10:3) and Mark (15:40) tell us that another woman named Mary and her husband, Alphaeus, are the parents of two men named James and Joses. Luke (6:15) also says that James is the son of Alphaeus. The problem is that John 19:25, describes Mary, not as the wife of Alphaeus but a man named Clop(h)as.
Papias, a disciple of the Apostle John and Bishop of Hierapolis (early 2nd Century CE) supports this theory in Fragment 10 of his writings, where he sums up the four different women named Mary in the NT, “(1) Mary, the Mother of the Lord. (2) Mary the wife of Clophas or Alphæus, who was the mother of James and of Simon and Thaddeus also known by his Hebrew name Jude, and of one Joseph. (3) Mary Salome, wife of Zebedee and mother of John the Evangelist and James. (4) Mary Magdalene”
Papias claims that Jesus’ brothers were actually the children of Mary the wife of Alphaeus/Clophas. Some scholars hold that both Alphaeus and Clophas were an attempt to Hellenize the Semite name Chalpai. Hegesippus ( CE) was a convert to Christianity from Judaism and tells us that Aphaeus/Clophas was the brother of Joseph making these four men Jesus’ cousins

3. Jesus’ Brothers Were Actually His Step-Brothers
Julius Africanus disagrees with Papias. Africanus believed that Clopas was indeed the husband of the second Mary and was very likely the father of a man named Simon but it was not the same Simon as Joseph’s son. He claims that Joseph had the four sons mentioned on the previous slide and two daughters (Salome and Mary ???)
But around the same time as Africanus, a popular piece of writing was circulating in early Christian communities called the Protoevangelium of James. A protoevangelium is a prequel to the gospel. This work gave names to Jesus’ grandparents by Mary, Anna and Joachim. Part 8 of this work describes how Mary spent her early years serving in the Temple
And Mary was in the temple of the Lord as if she were a dove that dwelt there, and she received food from the hand of an angel. And when she was twelve years old there was held a council of the priests saying: Behold, Mary has reached the age of twelve years in the temple of the Lord. What then shall we do with her, lest perchance she defile the sanctuary of the Lord?
To resolve the problem, it was decided that the widowers of the village would assemble and bring their walking sticks with them and cast them into a pile. One stick would be chosen at random and that widower would look after Mary and allow her to maintain her virginity. Joseph was one of these widowers. When his staff was chosen, a dove settled upon Joseph’s head (another version said his walking stick blossomed) so he was chosen. Part 17 of this work indicated that the widower Joseph had children by his first marriage
The protoevangelium was an explanation that satisfied Africanus while allowing Mary to remain aeiparthenos

4. Early Protestant Views on Mary Aeiparthenos
In many cases today, Protestant Christians simply believe that Mary had children with Joseph after Jesus. It is interesting to note what many of the early reformers thought about the issue.
The Latin text of the 1537 Smalcald Articles written by Martin Luther used the term "Ever Virgin" to refer to Mary. Luther never wavered from that belief.
Huldrych Zwingli (Reformed Swiss Reformer) directly supported perpetual virginity and wrote: “I firmly believe that [Mary], ... forever remained a pure, intact Virgin.”
John Wesley wrote: "... born of the blessed Virgin Mary, who, as well after as before she brought Him forth, continued a pure and unspotted virgin”
John Calvin was less emphatic in his open support of the idea, and neither flatly accepted or rejected it but he did caution against the idea of "impious speculation" on the topic of perpetual virginity and believed that the mention of the brothers and sisters of Jesus did not necessarily imply that Mary had other children
The trend in Protestant Christianity away from understanding Mary as “ever-virgin” expanded when the German Protestant scripture scholars in the 18th and 19th century began their critical review of the Hebrew and the Christian scriptures
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5. Points That Indicate That Jesus’ Brothers Were Not Mary’s Children
Scripture clearly states that Jesus was Mary’s firstborn child (a legal status) yet the references in Scripture to Jesus’ brothers portray them more as older brothers might be portrayed.
Jesus brothers did not believe in him (John 7:5, Mark 3:21)
When Jesus underwent his trials, brothers were nowhere to be seen
At the foot of the cross, Jesus tells John and Jesus’ mother Mary the famous words of John 19:26-27
When Jesus saw his mother there, and the disciple whom he loved standing nearby, he said to her, "Woman, here is your son, and to the disciple, "Here is your mother." From that time on, this disciple took her into his home.”
The tradition that Mary spent the rest of her years with John can be found in other early Church writings