Family residing in New York and Illinois.

Nelson Isham was born on May 17, 1805. He received his M.D. from the Medical Institution of Yale College in 1828. During the Civil War, he served as surgeon to the 97th Regiment, New York Volunteers. Isham married Delia Snell (b.1810) on April 8, 1830. Their son, Ralph Nelson Isham, was born in Manheim, Herkimer County, New York, on March 16, 1831.

Ralph N. Isham also studied medicine, and received his M.D. from Bellevue Hospital Medical College in 1854. He came to Chicago in 1855, and in 1859 took part in the organization of medical department of Lind University, later Northwestern University. During the Civil War he headed the United States Marine Hospital in Chicago and continued there for several years afterward. He eventually became chair of surgical anatomy and operative surgery at Northwestern University, and was a member of many medical boards and associations. He married Katherine Snow, daughter of George W. Snow, in 1856. They had four children, George S., Ralph, Katherine, and Harriet. Isham died of cancer in 1904.