There are some theories that: Otondo was in fact the first son of Imperial Prince Abo, but as the Imperial Prince was demoted to Dazai-fu (local government office in the Kyushu region) by being implicated in the Kusuko Incident, he was adopted by OE no Mototaka; and Otondo's mother who (from the Nakatomi family) was originally a waiting woman for Imperial Prince Abo, and after she got pregnant by Imperial Prince Abo, she became the wife of Mototaka and gave birth to Otondo, therefore Otondo may be the brother of ARIWARA no Yukihira or ARIWARA no Narihira.
なお一説によると、音人は実際は阿保親王の長子であるが、親王が薬子の変の連座で大宰府に左遷されたため、大枝本主の養子になった、あるいは、母中臣氏はもともと阿保親王の侍女で、阿保親王の子を身籠もった後に、本主の妻となり音人を産んだといわれ、在原行平や在原業平らと兄弟だともされる。