Family
John was the son of Saint Stephen the Blind, Despot of Serbia (born 1417, blinded in 1441 by order of the Ottoman Sultan Murad II, died 1476), and of Saint Angelina, daughter of the Albanian prince George Arianiti, whom Stephen married in 1460. His elder brother George (Đorđe) Branković took monastic vows under the name Maximus.
John married Jelena Jakšić, a Serbian noblewoman. By the account in Wikipedia they had four daughters and no surviving male heir; one daughter, Jelena, married Prince Peter IV Rareş of Moldavia. The whole family — Stephen, Angelina, George (Maximus), and John — is venerated together as a holy household of the Branković dynasty.