The Sunday of the Ancestors celebrates the men and women in Jesus' family tree. Just like ordinary families, there are some people of whom we know little, and some that we'd rather not know about at all!
Matthew brings in the Gentile women who helped perpetuate the line of David with unusual actions which disturbed the Jews but which God blessed abundantly. This genealogy shows that Jesus is open to all people, of all backgrounds, just as His Church is!
Both the Eastern and Roman Churches have Jesse Trees, which depict the ancestors of Jesus through his foster-father St. Joseph. Joseph was Jesus’ legal father, and so the ancestors are men and women from the genealogies in Matthew and Luke. These Trees are based on the prophecy of Isaiah: “There shall come forth a shoot from the stump of Jesse, and a branch shall grow out of his roots.” (Is 11:1), and thus will show Jesse as the base of the Tree.
More common among Western Christians, the image of Matthew’s and Luke’s genealogies first appeared in Byzantine icons from the 12th – 16th centuries in the Byzantine Empire itself. The Trees can often show Our Lady in the center of the Tree, holding the Infant Jesus in her lap, based on St. Irenaeus of Lyons who hailed Mary as the “rod” of Jesse, since it is she who conceived Christ through the Holy Spirit, and Jesus is the flower of the rod.