Brant Gardner argues based on Ether 14:1–2 that the Jaredites were probably polygamists.
Brant A. Gardner, Second Witness: Analytical and Contextual Commentary on the Book of Mormon, six vols. (Salt Lake City: Kofford Books, 2007), 6:313–314
The reference to 'every man" defending "his wives and children" again suggeststhe possbility of polygamy among the Jaredites. . . . When combined with the evidence from the cultural area, it seemsprobable that polygamy was indeed practiced, though condemned only when Moroni was describing a wicked king. (Sec commentary accompanying Ether 10:5.)