Matthew probably mentioned brothers in the case of Judah and Jechoniah to show that their time was a period of great change in Israel’s history. For Judah, the mention of his brothers shows that the blessing promised to the patriarchs applied to all the tribes descended from them (Matthew 10:6; Matthew 19:28).
The fact that it is only in Matthew 1:2 and Matthew 1:11, with Judah and Jechoniah, that brothers of descendants are mentioned probably serves to indicate that their generations represented a decisive turning point in history. In Judah’s case it points to the fact that in his generation the blessing was not only limited to one man, but extended to the families of all twelve sons from which the twelve tribes of Israel sprang (Matthew 10:6, Matthew 19:28).1
2 Abraham was the father of Isaac, and Isaac the father of Jacob, and Jacob the father of Judah and his brothers,