Dorothea Bleek was born on 26 March 1873, the fourth in a line of five daughters. Soon after she was born, her family moved from their home, The Hill, to their new residence a short distance away in the same village of Mowbray, just outside colonial Cape Town. The rambling new property, called Charlton House, was located across from the existing student apartment complex, now known as Forest Hill, in the Main Road. Demolished in the 1960s to make way for a teachers’ training college, Charlton House was just a few blocks from the Baxter Theatre in Rondebosch, on the edge of the middle and upper campuses of UCT, where Dorothea would one day hold an honorary readership.

Dorothea was born into an unusual domestic situation. Her father, Wilhelm, was widely known within European intellectual circles despite his distant location at the Cape Colony. By the early 1870s his networks and correspondents included the leading thinkers and social scientists of the era, including his cousin the evolutionist and naturalist Ernst Haeckel, the philologist Max Müller, Charles Darwin and the English biologist Thomas Huxley. At the time of Dorothea's birth, Wilhelm's study of the ‘click languages’ of southern Africa had progressed, as had the process of collecting folklore from bushman prisoners who had been sentenced, mostly for stock theft and poaching, but in one case for murder, to hard labour at the Breakwater Prison. Some of the prison buildings, albeit repurposed, can still be seen along Portswood Road, close to Cape Town's glitzy V&A Waterfront entertainment and shopping complex. Wilhelm had obtained permission from the colonial government to have selected prisoners live at his home so that he could work intensively with them to study their language, folklore and cosmology. As is well known, Lucy Lloyd, the sister of Wilhelm's wife Jemima, became involved in the project. From early on, Lucy assisted Wilhelm with interviews and transcriptions and in time became schooled in the /Xam language and its nuanced phonetics. Lucy continued the project after Wilhelm Bleek's early death in 1875.