John Theodore Seiffert was born on September 11, 1900 (although some documents say 1903), in St. Paul, Minnesota. His parents were Joseph and Mary Seiffert. Joseph Seiffert was born in Germany and was brought to the United States by his father, Theodore, in 1879. Joseph’s wife, Mary Auvley, was born in Confluence, Pennsylvania, to native born parents. Sometime before 1910 the Joseph Seiffert family, including John and his older sister Marie, moved to Portland, Oregon. They are shown on the 1910 census residing in North Portland on N. Minnesota Ave. The family, however, did not own that home until 1917.

In 1919 the then nineteen year old John T. Seiffert attended Portland’s School of Drama and Expression. Invitations show the school holding three recitals in 1919 and 1920. On September 19, 1920, the press took note of Seiffert’s stage debut in a review of the play “at 9:45”, a murder melodrama performed at Portland’s 3rd Avenue Baker Theater : “The murdered boy is a newcomer, John Seiffert”. A scrapbook in the Seiffert collection contains a number of notices, reviews and notes of Seiffert’s career. Seiffert played a number of roles at the Baker Theater before he joined road theater companies that took him from theaters in Vancouver and Seattle, Washington, to Utica, New York, and St. Paul, Minnesota. He is noted as an actor and director in numerous plays.

Around 1933 Seiffert moved to San Francisco and was noted as performing and directing in small theaters. One July 1933 notice shows a theater company bearing his name, the John Seiffert Players, performing in a basement theater on Geary Street. He aslo conducted acting classes and led a group of actors performing drama on San Francisco radio station KJBS. At some point Seiffert converted the Geary basement theater into a ballroom dancing school, the Irene Studio. In 1941 he was certified as a teacher of "Absolute Science," possibly related to the Christian Science church.

In April, 1938, Seiffert married Olive (Southcott) Simmons of San Francisco. She was the daughter of W.H. Southcott, once the mayor of Grass Valley, California, and his wife Jessie (Buckett) Southcott. Olive's obituary notes that she was a dance instructor and worked together with John Seiffert in San Francisco for about 20 years. This corresponds to evidence that the Seifferts left San Francisco in 1958 and moved to Portland that year. Portland City Directories begin listing John Seiffert’s residence at his parent’s Minnesota Avenue home in 1958. His occupation was noted as a salesman at Meier & Frank department store ithat year and 1960. The directories did not list John’s occupation in 1961, and by 1964 he is shown as retired. In 1960 the State of Oregon bought the Seiffert’s home, and the family purchased a new home at 6607 Borthwick.

John T. Seiffert died in Portland on August 19, 1972. The death certificate notes that he died of congestive heart failure and that he was a diabetic. He was buried in Portland’s Memorial Cemetery. His widow Olive continued to live in the Borthwick home and died in Portland in on May 16, 1994. There is no evidence that the Seifferts had any children.