It is believed that at the Ichinomiya of Shimotsuke Province which was supposedly under control of the Keno (or Kenu) clan, Soen took a seat of honor which was superior to Shinto priests, thereby making it possible to infer that Soen may be related to the Keno clan (i.e. Soen was possibly an illegitimate child of the father of the Fujiwara clan and the mother of the Keno clan).
宗円は毛野氏の支配下にあったと推測される下野國一之宮において、その神職者より上座に座したことが伝えられており、このことから毛野氏の流れを汲む人物（毛野氏への藤原氏の落し種）と推察されている。