Minnie Gregg was the daughter of Livingston Gregg and Kathryn White. When she was only nine months old, her mother deserted her and her father and ran away with Wellington Gregg, Livingston's oldest brother, with whom she had always been in love (per Kathleen Moore's notes). Minnie went to live with her grandparents, Angeline (Durbin) and Riley Gregg, and was raised by them.

Minnie married Edmund Smith Kilburn in 1896. Their sons were Richard Guy Kilburn, born in 1898, and Gregg Yancey Kilburn, born in 1899. Minnie worked at the Anna Head School in Berkeley, with Mae Blakeney Moore and Mary Wilson. She introduced her son Richard Guy Kilburn to Mae's daughter Marjorie Moore, and they were married.