In 1893, "Busshari-sojo-keizu" (The genealogy of Buddha's ashes) written in 1235 was found at Konomiya-jinja Shrine in Shiga Prefecture, and it suggested a persuasive theory that the sister of Gion no nyogo, who was in Cloistered Emperor Shirakawa's favor and was impregnated by him, was granted to Tadamori, and Kiyomori was born, and after Kiyomori's mother died, her older sister Gion no nyogo raised him as her own son.
明治26年（1893年）になって、滋賀県・胡宮神社所蔵の文暦2年（1235年）の日付を持つ『仏舎利相承系図』が発見されたことで、祇園女御の妹が白河法皇の寵愛を受けて懐妊後に、忠盛に下賜されて生まれたのが清盛であり、母が亡くなったので姉の祇園女御が猶子として養育したという説が有力となった。