Since Junshi was called 'Sugawara no kimi' ("Yamato Monogatari" (Tales of Yamato)), there is an theory that Junshi's mother was SUGAWARA no Tomoko, who was a kokyu (wife, possibly a court lady called koi) of Emperor Koko and a daughter of SUGAWARA no Koreyoshi, and she was adopted by Emperor Uda later.
また、順子は「菅原の君」と呼ばれていたことから（『大和物語』）、光孝天皇の後宮（更衣(女官)か）で菅原是善の女である菅原類子を順子の母と擬定し、のちに宇多天皇の養女になったとする見解がある。