Jesus’ instructions to John to take care of Mary, as his mother, upon his crucifixion seem to imply that Mary had no other children.
Also... with 5 children in on the discipleship game with Jesus. How is there no role for Joseph, their father on earth, in their formation and ministry?
Isn't there a more straightforward explanation? None of his brothers believed in Him and were not at the crucifixion, John WAS there.
It implies that her other children were NOT the eldest son. It was Jesus' position as the eldest in the Jewish home to take care of His mother. Most likely He had John do it because 1) John was a nephew of Mary's 2)Jesus' brothers, who thought Jesus a nut, had scattered to the four winds & did not yet believe in Him as the Christ -- see James and Jude; therefore, Jesus was not going to leave Mary's care to them. We don't know how much younger they were than Jesus, there could have been sisters in between.