This definition is implausible because some of Imperial Prince Motoyasu's sons were given the surname of Minamoto no Ason and became Ninmyo-Genji, such as MINAMOTO no Kaneji (源兼似), MINAMOTO no Kanehito (源兼仁), MINAMOTO no Chogan (源朝鑑), MINAMOTO no Yasumochi (源保望), and MINAMOTO no Yoshimichi (源由道).
しかし、本康親王の皇子でも源兼似・源兼仁・源朝鑑・源朝憲・源保望・源由道のように源朝臣を賜姓されて仁明源氏となった者もいる。