Georg Ratzinger died on 1 July, aged 96. The two brothers were ordained priests on the same day in 1951.
Benedict, who was elected in 2005 to succeed the widely popular Pope John Paul II after a reign of nearly 27 years, shocked the world and even his closest aides on 11 February 2013, when he announced in Latin he was stepping down.
He told a gathering of cardinals that he was too old and frail to lead an institution with more than 1.3 billion members.
At the time of Benedict's resignation, the Vatican was mired in a raft of financial woes, sexual abuse scandals, and infighting among bureaucrats that led to leaks of important documents.
Benedict said his resignation was due exclusively to health reasons.
Hardline conservatives in the Church who have been alarmed by Pope Francis' progressive moves have looked to Benedict as their standard bearer. This forced the former pope on several occasions to remind them that there is only one pope - Francis.