His daughter Yoshiko NAKAYAMA was Naishi no suke (a court lady of the first rank) of the Emperor Komei and delivered the Emperor Meiji, so that Tadayasu was a maternal relative of the Emperor Meiji.
娘の中山慶子が孝明天皇の典侍で、明治天皇を産んだことから、忠能は明治天皇の外戚に当たる。