Hoffmann was born on May 17, 1871,[1] at Heidelberg (German Empire), the daughter of Walter and Mary Sara Silver (née Fraser) Wesselhoeft.

[2][3] Her father was a German-born doctor who at the time of her birth had left his medical practice in Halifax, Nova Scotia to volunteer his services after the outbreak of the Franco-Prussian War.

He returned to North America in early 1873 and opened a general practice in Cambridge, Massachusetts, where Gertrude was raised along with her six siblings.

[10][11] Gertrude's youngest sister, Eleanor Wesselhoeft (1882–1945),[12] was a stage actress and playwright who also found some success late in life as a character actor in Hollywood.

Trudy married British composer Sir Arthur Bliss on June 1, 1925, in Santa Barbara, California and moved to London, England, where she lived until her death in 2008.

Among her credits are such films as Alfred Hitchcock's Foreign Correspondent, The File on Thelma Jordon (1950), Caged (1950), and The War of the Worlds (1953).