When interpreting a verse from genealogies in the Book of Chronicles becomes an essential point to the laws of inheritance -- when the son, Yair, had cities (read: land) that his father Seguv seems not to have had. So the inference is that Yair inherited from his mother. Also, the Gemara goes back to the cases of a woman who inherits from her father and has to marry within the same tribe... which complicates matters immeasurably, especially if and when the likely case is that the parents are not necessarily from the same tribe.