However, some say that ABE no Yoshimasa was the legitimate son of Seimei while Yoshihira was the elder brother of Yoshimasa with a different mother, given that the issues; the age difference between Yoshihira and yoshimasa was just a year; the post of Onmyo no kami which was supposed to be appointed to the legitimate son (the eldest son) was assumed by the second son of seimei, Yoshimasa.
しかしながら、吉平と吉昌の生年の差がほとんど無い（1年差）ことや、世襲が慣例化していた時代に本来ならば嫡男が任ぜられるべき陰陽頭の職を次男であるはずの吉昌が就任していることなどから、安倍吉平は庶兄（異母兄）であり、安倍吉昌が晴明の嫡男ではないかとの説もある。