However, in the midst of Heian period, as hereditary government office system developed and the government post, regarded as a kind of interest, became taken over by heredity, particular clans ('hakase family') that took up the post of instructors by heredity emerged.
だが、平安時代中期に官司請負制の進行とともに官職が一種の利権として認識されて世襲が進むと、こうした教官（博士）の地位を世襲する特定の氏族（「博士家」）が出現するようになる。