Ether 1:40–41 and 6:20 in the Kirtland 1837 edition of the Book of Mormon describe the families of Jared and the Brother of Jared.
Joseph Smith, Jr., trans., The Book of Mormon: An Account Written By the Hand of Mormon, Upon Plates Taken from the Plates of Nephi (Kirtland, OH: O. Cowdery & Co., 1837), 569, 579
And it came to pass that the brother of Jared did cry unto the Lord according to that which had been spoken by the mouth of Jared. And it came to pass that the Lord did hear the brother of Jared, and had compassion upon him, and said unto him, go to and gather together thy flocks, both male and female, of every kind; and also of the seed of the earth of every kind, and thy families; and also Jared thy brother and his family; and also thy friends and their families, and the friends of Jared and their families. And when thou hast done this, thou shalt go at the head of them down into the valley, which is northward. And there will I meet thee, and I will go before thee into a land which is choice above all the land of the earth.
. . .
And accordingly the people were gathered together. Now the number of the sons and the daughters of the brother of Jared were twenty and two souls; and the number of the sons and daughters of Jared were twelve, he having four sons.