When Jan Karel Lankhorst was born on 9 June 1874, in Deventer, Overijssel, Netherlands, his father, Jan Lankhorst, was 25 and his mother, Hendrika Jacoba van Wijhe, was 22. He married Aagje Kranendonk on 6 September 1899, in Gouda, South Holland, Netherlands. They were the parents of at least 1 son and 2 daughters. He died on 12 February 1955, in Gouda, South Holland, Netherlands, at the age of 80.