Isak married Dorthea Caroline "Dora" Nagel. Dorthea (daughter of Edward G. Nagel and Mathilda Lily Heinz) was born 2 Jul 1902, Chicago, Cook, Illinois, USA; died 1981, St. Charles, Kane, Illinois, USA; was buried , Garfield Cemetery, Campton, Kane, Illinois, USA. [Group Sheet]

1. Wesley Johnson was born 24 Jul 1924, Wasco, Kane, Illinois, USA; died 5 May 1975, Wasco, Kane, Illinois, USA; was buried , Garfield Cemetery, Campton, Kane, Illinois, USA.
2. Kenneth E. Johnson was born 8 Jan 1932, St. Charles, Kane, Illinois, USA; died 10 Dec 2015, Chicago, Cook, Illinois, USA.