He was a son of Romanos with his first wife Anne, a daughter of Alusian,[1][2] and hence excluded from the line of succession when his father married the empress-dowager Eudokia Makrembolitissa in 1068.
The then kouropalatissa Anna Dalassene (later, regent of the empire), wife of the brother of the late Emperor Isaac I Komnenos, despised the Doukas imperial family.
According to perceptions of Anna Dalassene, the Doukas men had usurped the imperial dignity by tricking emperor Isaac into resigning and her husband, the kouropalates John Komnenos, into refusing the throne.
Romanos Diogenes was raised to the imperial throne, having to marry the Doukas dowager empress Eudokia Makrembolitissa.
Emperor Romanos' son received the daughter of kouropalates John Komnenos and kouropalatissa Anna Dalassene as his bride.