1930 US Census
Seattle, King Co., Washington
Shouldice, Harry, head, aged 48, married, for first time at age 36, b. Canada-English, parents b. same, emigrated 1920, alien, salesman, portrait studio
Shouldice, Nettie(?), Wife, aged 36, married, for first time at age 32, b. Washington, parents b. Maine, saleslady, portrait studio
Shouldice, Gordon, Son, aged 20, single, b. Canada, parents b. same, printer, printing office
Shouldice, John H., Son, aged 18, single, same info, assistant manager, theatre
Shouldice, Harold G., Son, aged 16, single, same info
1911 Canadian Census
Vancouver, British Columbia
Shouldice, Harry, Head, married, b. May 1881, aged 30, b. Ontario, Irish, Angican, salesman
Shouldice, Violet, Wife, married, b. September 1889, aged 21, b. U.S., emigrated 1908
Shouldice, Gordon, Son, single, b. January 1910, aged 1, b. Saskatchewan
British Columbia Vital Statistics website has a death for a John Herbert Shouldice on 19 June 1971, aged 59, in Victoria, British Columbia. Getting a copy of the death record may indicate if he was married or not.
I also found the WWII Enlistment Record for a John H. Shouldice in California on 23 February 1943, born about 1911, living in Sacramento, married, gives his occupation as an athletic instructor or skier.
I found the three kids, Gordon, John & Harold all arriving in Seattle, in 1920, bound for Aptos, California; giving their father, Henry H. Shouldice in Vancouver, as their next of kin. Headed for their Aunt, Mrs. Eileen Thorburn, of Aptos, California.
Their mother must have passed away, and Henry (Harry) was sending the boys to their aunt. Gordon was born in Maymont, Saskatchewan, and the other boys were born in Vancouver.