Born in England c. 1880, John Sellen had settled in Seattle, WA, by at least 1913. (Sellen's WA Death Certificate indicated that he was born in 1880. The U.S. Census of 1930, he was born c. 1890.) In 1910, John Sellen, a civil engineer for the railroad, lived on Mercer Island, WA, with his mother, Mary. According to the U.S. Census of 1930, he lived at 8111 10th Avenue NE in Seattle, with his wife and two children. The census indicated the house to have been worth a modest $7,000 at this time. Sellen lived in the Territory of AK at Cordova from at least the year 1917-1920.

John's parents, William(born c. 1850) and Mary E. (born c. 1854), came from England to the the Port of New York on 08/25/1884 aboard the S.S. Alaska. The family also included John's sister, Edith G. Sellen (born c. 1876) and another sibling. Only William, Mary, John and Edith arrived on the Alaska in 1884.

Sellen married Blanche H. Charon, c. 1911. Blanche had come from MI; her parents were both French-Canadian.

John and Blanche had two children, John Henry, Jr., (born in Seattle, WA, 07/17/1913-died Bellevue, WA,11/15/1983) and Frances J. (born in AK c. 1917).