That Mary had other children also seems indicated by the incident that occurred when Jesus was twelve years old and Joseph took his family to Jerusalem for the festival. On the way back they had traveled a whole day before Mary noticed that Jesus was not with them. Had Jesus been her only child (and miraculously conceived at that), could we imagine her maternal instincts being so dormant that she would have started out without him and not missed him for a whole day? But if by this time she had six or more children by Joseph, we can imagine her having been so busy that she might not have missed Jesus for a whole day.Luke 2:41-50.
True, the question might be asked, If Mary had other children, why did Jesus entrust his mother to his apostle John instead of to her other children? For one thing, his other brothers may not have been at the site of his impalement, they apparently not yet having become believers. Also, of his disciples, John was closest to Jesus, and had a spiritual relationship with him that exceeded any natural relationship.John 19:26, 27.