Alexey Mikhailovich Ridiger's father Mikhail Aleksandrovich Ridiger (1900–1960), born in Saint Petersburg, was a descendant of a Baltic German noble family. His ancestor Captain Heinrich Nikolaus (Nils) Rüdinger, the commander of a Swedish fortification in Dünamünde, Swedish Livonia, was knighted by Charles XI of Sweden in 1695. After Swedish Estonia and Swedish Livonia became part of the Russian Empire in the aftermath of the Great Northern War in the beginning of the 18th century, another forefather of Alexy II, Friedrich Wilhelm von Rüdiger (1780–1840), adopted Orthodox Christianity during the reign of Catherine II of Russia. From the marriage with a Polish woman Sophie Dorothea Jerzębska was born the future Patriarch's great-grandfather, Yegor (Georgi) von Rüdiger (1811–1848).