Our received version of the Old Testament also contains genealogies, but they are through Judah, not Joseph. The Josephite genealogy is a further indication of the differing source of the brass plates text from that which we use today. As Sorenson points out, this genealogy itself points to a Northern Kingdom origin for the brass plates (Sorenson, John L. "The "Brass Plates" and LDS Biblical Scholarship" undated mss, p. 5).
Verse 16's indication that Laban kept the records because he too was a descendant of Joseph tells us that the record was related to the tribe of Joseph, and that the task of preservation (if not the addition of texts) was in the hands of that tribe.
The Brass Plates as a Model for the Book of Mormon: We have the information about the brass plates because we have the Book of Mormon. It is possible that we have the Book of Mormon because the Lehites have the brass plates. They may have provided many of the models used in the development and transmission of the Book of Mormon texts up to the time of Mormon's compilation.
The first obvious similarity is the preservation of the sacred text on metal. The brass plates and Nephi's gold plates are both structurally similar. It may even be that Nephi's use of gold was a "poor man's" attempt to copy the brass. The strength of brass would exceed that of gold, and the refinement of gold might be a simpler process than the combination of elements required to produce brass (or bronze). In a Mesoamerican context, gold may even have been sufficiently more plentiful that is was the logical available choice. From a physical standpoint the brass plates provided a model for the Nephite plates.
The language of the Nephite plates may also have been influenced by that of the brass plates. As indicated before, there is reference to the necessity of having an understanding of Egyptian to be able to read the brass plates. If they were written using any form of Egyptian, the decision to use Egyptian, or later reformed Egyptian on the Nephite plates would be clearly taking a model from the brass plates.
The brass plates contained a collection of the works of individual prophets. Also in the Nephite plates, the tradition was kept that each person writing on the plates would contribute their "book" (a tradition from which the small plates departed at the end - see the Book of Omni). The construction of a canon which consisted of the collected works of individuals follows the brass plates, though it also follows any other set of scripture which would have been known to Lehi.
The brass plates were kept (and perhaps maintained) by the lineage of Joseph. They appear to have a greater tie to Joseph than to Judah. This lineal affiliation of the record may have influence the lineal affiliation of the Nephite record. The small plates clearly had a specific lineal history while they were being maintained. That tradition, of having a set of scriptures related to a particular lineage, would have fallen in line with the model of the brass plates.
The dual transmission line of the large and small plates may also have some connection to the model of the brass plates. Clearly the brass plates followed a lineal transmission, and were known to the members of that lineage. Just as clearly, however, there were other sets of scripture available (if only that of the line of Judah). We therefore have a model of multiple sets of scripture which could serve for the large/small plates distinction. Since the large plates became the politically transmitted set, there may have been precedence in Jerusalem for an "official" record which followed the political power, with the brass plates representing the smaller lineage tradition. That conceptual model fits directly with the known transmission lines of the large and small plates in the Book of Mormon.