Jien was the child of FUJIWARA no Tadamichi and Kaga-no-tsubone (a daughter of FUJIWARA no Nakamitsu) and a younger brother of Kanezane KUJO, the sixth child of Tadamichi.
慈円は藤原忠通と加賀局（藤原仲光の娘）の子で忠通の第六子、九条兼実の弟。