Background
Hoernlé was born in Secundra, Agra, British India on the 14th November, the son of a Protestant missionary reverend, from a German family who had provided a number of recruits for the Church Missionary Society in the area. He descended from a long line of missionaries which included both linguists and revolutionaries. His father Christian Theophilus Hoernlé (1804–1882) translated the gospels into Kurdish and Urdu, Hoernlé was therefore a British subject by birth.
He was sent to Germany and his grandparents, at age 7, and was initially educated there.