The passage does not say one way or the other.
Matt 12
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.
Mark ch 3
32 And the multitude sat about him, and they said unto him, Behold, thy mother and thy brethren without seek for thee.
33 And he answered them, saying, Who is my mother, or my brethren?
34 And he looked round about on them which sat about him, and said, Behold my mother and my brethren!
In matt he stretched his hand toward his disciples.
In fact both passages makes it very plain.
Three different words used to describe those present.
The crowds or multitude
His mother and his brethren
His disciples
We do not know if his disciples were his mother/brethren or if they were among the crowd.
It just doesn’t say what is wanted here.
It does not say those who came to speak to him were not his followers.
What we are to learn from this, the take away if you will,
is that those whosiever does the will of God is his mother and brethren.
This is not a rebuke of Mary. It certainly does not mean that Mary was not a follower.
Mary comes to speak to him, he is surrounded by people.
The word is passed up that she and his brethren are there wishing to see him.
He uses their appearance to tell the crowd that when one does the will of his Father in heaven, one is his brother or sister or mother.
We are not told what immediately follows this exchange.
Often times people read into passages what they want it to say rather than reading it, considering the time and place in the story and trying to discern why the writer felt the need to include it.
It is just not as plain as one would like to believe.