In 2 Nephi 3:4, Lehi says, "I am a descendant of Joseph." From the Book of Mormon, we learn that Lehi was a descendant of Joseph through his oldest son Manasseh. From Erastus Snow in the Journal of Discourses quoting Joseph Smith and also Joseph Fielding Smith in Answers to Gospel Questions, the Prophet Joseph informed us that Ishmael was of the lineage of Ephraim. He brought his daughters and his two sons. Lehi’s sons married Ishmael’s daughters and perhaps Ishmael’s sons had already married Lehi’s older daughters, and so both branches of Joseph’s posterity were represented. The people of Lehi were pure Josephites. That is why this can be called the stick of Joseph. It is a record of descendants of Joseph.