Kiyomori was the first child of Tadamori; however, because his biological mother had already died, there was a possibility that Tadamori's second son, Iemori, who was born to Muneko, might become the heir with the support of his mother.
清盛は忠盛の長子だったが生母はすでに死去していたため、宗子の産んだ次男・家盛が母の後押しで嫡子となる可能性もあった。