Morokazu was from the family of Sadachika line of the Myogyodo-Nakahara clan that produced OE no Hiromoto (before he changed his name, he was NAKAHARA no Hiromoto); and Morokazu's father Moroshige was a cousin of NAKAHARA no Chikayoshi (later, he changed his name to FUJIWARA no Chikayoshi) and OE no Hiromoto.
大江広元（中原広元）を出した明経道中原氏の庶流貞親流で、師員の父師茂は中原親能（藤原親能）、広元（大江広元）兄弟の従兄弟にあたる。