She was the daughter of Hermina Maria (Veraar) and Norman Isaac Ewing. Her father was American and her mother was Dutch. Her father was the son of African-American parents. He performed as a Sioux Native American, and had even been described as a Native American chief in newspapers. On
Finding Your Roots with Henry Louis Gates, Jr. (2012), a DNA test showed Maria's daughter Rebecca to be of 91% European and 9% African genetic ancestry. Maria's paternal grandfather, John William Ewing, who had been born into slavery, became prominent in D.C. circles in the 1870s, and her three times great-grandfather was Revolutionary War veteran Bazabeel "Basil" Norman, a free black man.