Gerontius married Adamanta Chubb and had twelve children; eight sons: Isengrim III, Isumbras IV, Hildigrim (great-grandfather to Peregrin Took and Meriadoc Brandybuck), Isembold, Hildifons, Isembard, Hildibrand (great-grandfather to Fredegar Bolger), and Isengar; and four daughters: Hildigard, Belladonna (mother to Bilbo Baggins), Donnamira, and Mirabella (grandmother to Frodo Baggins). He was Thain for 72 years at the time of his death in TA 2920 (SR 1320).