From what EGW has written, some of them were older than Jesus, making them Joseph's children, since Jesus was Mary's first.
There could have been some younger as well though.
Is there any other possibility?
If Joseph had a family before he married Mary and she concieved Jesus of the Holy Spirit, a number of things would fall into place. for instance, Joseph was not the biological father of Jesus, but and children he had would be seen as Jesus' brothers or sisters. See texts already quoted. James the brother of Jesus became the leader of the Jerusalem church. According to early church history, Joseph is thought to have been around 50 and Mary about 16 at the time of Jesus' conception.
If Joseph already had a family from a previous marriage, it would answer the question of how Joseph could leave Nazareth and travel to Bethlehem and then onto Egypt and then after the death of Herod come back to Nazareth.
Jesus grew up helping his father in the family building business. (The word used translated carpenter also means builder). Joseph would have become too old to work the business by the time Jesus was in his late twenties. He stayed supporting his family until he was about 30, this would give Mary's other children time to grow up and take on the business.