Although the Fumi clan (written as 文氏 or 書氏) holding Atai as their kabane originated from the Yamatonoaya clan which had been Immigrants to ancient Japan, the detail of Jokaku's genealogy is unknown.
直姓の文氏（書氏）は、東漢氏に属する渡来系の氏族だが、その中での成覚の系譜は不明である。