According to "Utsunomiya Shishi" (The history of Utsunomiya City) and "Seishi Kakei Daijiten" (a large dictionary of Japanese surnames), however, the fact that Soen was a descendant of FUJIWARA no Michikane was made up by his descendants and it is assumed that the Utsunomiya clan was descended from the Nakahara clan or a descendant of the ancient Kenu clan.
しかし『宇都宮市史』や『姓氏家系大辞典』では、宗円を藤原道兼の子孫とするのは後世の仮冒で、宇都宮氏は中原氏の出、あるいは古代の毛野氏の後裔と想定している。