She was born Theodora Benton Eliot McCormick in Brooklyn to Eliot McCormick (1849-1891) and Laura Case Brenton McCormick (1869-1923), a seventh-generation descendant of Roger Williams. You will notice that her father was twenty years older than her mother and died just a year after Theodora's birth, when he was about 42 (it is claimed Theodora was christened at her father's funeral).
Theodora's widowed mother married Charles MacDonald, a lawyer and Wall Street broker. The family moved from Booklyn to Yonkers and bought the Hudson River mansion Seven Pines, previously owned by a nephew of William Tecumseh Sherman, who named it for seven huge pines on the estate, which reminded him of the Civil War battle, so the story goes. A 1945 newspaper story stated that one of the pines was 106 feet tall and more than 150 years old.
The French Chateau style house was originally built in 1845, was three stories high with a cellar and sub-cellar and had twenty-eight rooms, including a tower room, and a dozen fireplaces. It has since been demolished, but a neighboring house, Glenview (now the Hudson River Museum), survives to give an idea what it may have looked like.
Although brought up in circumstances of wealth, DuBois, according to this account of her life, "hated her stepfather all her life" and felt "socially isolated" in Yonkers (well, who doesn't, darn it all). She planned to enroll at Vassar, despite opposition from her mother and stepfather. However, after being accepted there, she came down with tuberculosis and never did go.
In 1918 she married Delafield DuBois, a Harvard graduate and electrical engineer and researcher. She published her first short story in 1920 and from then on wrote professionally for many decades. She wrote most of her detective novels in the period when her husband had taken a position as a researcher with Yale Medical School and the couple and their children lived in New Haven, Connecticut.
The influence from her own life on her mysteries is clear, for her sleuthing couple consists of Anne McNeill and her husband Dr. Jeffrey McNeill, a researcher at a Connecticut medical school. DuBois was one of the early creators of a sleuthing couple in the wake of Dashiell Hammett's Nick and Nora Charles (of Thin Man fame), but where some sleuthing couples have thrived in reprints in the last several decades (the Roos' Jeff and Haila Troy and the Lockridge's Pam and Jerry North come to mind), DuBois' McNeills have not. I have my theories as to why, which I will explore tomorrow (or later today!), when I post my review of Death Is Late To Lunch (1941).