I believe Mary had children after Jesus.
54And when he was come into his own country, he taught them in their synagogue, insomuch that they were astonished, and said, Whence hath this man this wisdom, and these mighty works?
55Is not this the carpenter's son? is not his mother called Mary? and his brethren, James, and Joses, and Simon, and Judas?
56And his sisters, are they not all with us? Whence then hath this man all these things?
57And they were offended in him. But Jesus said unto them, A prophet is not without honour, save in his own country, and in his own house.
58And he did not many mighty works there because of their unbelief(Matthew 13:54-58).
The people in the synagogue was amazed at Jesus' wisdom and His works,for they thought He was a mere man,by pointing out His immediate family,Father,Mother,and His brothers and sisters.
The point here is they were pointing out His immediate family,making it a point of how can Jesus have such wisdom and works,seeing He was born in this world like everyone else,by the fact He had a mother,and father,and sisters,and brothers.
It is not mentioning cousins,and the fact that it mentioned His mom and dad first tells that what follows is His brothers and sisters.
Also the disciples pointed out to Jesus as He was speaking to a crowd,that His mother and brothers were outside the crowd,wanting to talk to Him,which is His immediate family,and Jesus pointed out that speaking to the crowd of spiritual matters was more important than speaking to them,and whoever does the will of the Father is His family.
It is talking of His immediate family wanting to talk to Him.
There is a Greek word for cousin but it is not used but brother is used.
36And, behold, thy cousin Elisabeth, she hath also conceived a son in her old age: and this is the sixth month with her, who was called barren(Luke 1:36).
58And her neighbours and her cousins heard how the Lord had shewed great mercy upon her; and they rejoiced with her.
The Bible calls Elisabeth the cousin of Mary.The Bible calls these people cousins,so if it meant Jesus' cousins it would of said so.
If brothers mean cousins,then how come every time Jesus' mother comes to see Him,or she is mentioned,the brothers,or cousins so they say,are almost always with her,like they do not have their own mom and family to hang out with,and why are they not with Jesus but always with Mary.
This is a fundamental error of building the foundation from the roof down.
They already had the doctrine of Mary being the co-redeemer,and mediatrix of all graces,so they must portray her as a virgin to keep that doctrine.
They had the doctrine of Mary being those things,which she must stay a virgin,and so they try to convince people they are cousins so they can hold unto the doctrine that Mary was always a virgin,because they believe she is co-redeemer and mediatrix of all graces.
17And whatsoever ye do in word or deed, do all in the name of the Lord Jesus, giving thanks to God and the Father by him(Colossians 3:17).
6Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me(John 14:6).
12Neither is there salvation in any other: for there is none other name under heaven given among men, whereby we must be saved(Acts 4:12).
But we know that Jesus is the only savior and Mary cannot help us.
46While he yet talked to the people, behold, his mother and his brethren stood without, desiring to speak with him. 47Then one said unto him, Behold, thy mother and thy brethren stand without, desiring to speak with thee.
48But he answered and said unto him that told him, Who is my mother? and who are my brethren?
49And he stretched forth his hand toward his disciples, and said, Behold my mother and my brethren!
50For whosoever shall do the will of my Father which is in heaven, the same is my brother, and sister, and mother(Matthew 12:46-50).
27And it came to pass, as he spake these things, a certain woman of the company lifted up her voice, and said unto him, Blessed is the womb that bare thee, and the paps which thou hast sucked.
28But he said, Yea rather, blessed are they that hear the word of God, and keep it(Luke 11:27-28).
And we know that Jesus treated all the saints on the same level as Mary,and all the saints were all equal as Mary,and Jesus put Mary in the same boat as all the saints,and did not exalt her above other saints,and Jesus called Mary,woman,when dealing with her,and that is because God gets the glory,not Mary,and everybody has their labor from God to do the Lord's work.
But that is all it is,they view Mary as co-redeemer and mediatrix of all graces,so she must remain a virgin to be those things,so brothers must mean cousins and not children from Mary.