Gretchen Sibley was raised in Los Angeles. She remembered visiting museums as a child with her parents, who were interested in art. She trained as a teacher, and taught at a junior high school in Los Angeles for three years, while working on an advanced degree in zoology at the University of Southern California. She wrote a thesis, "A Comparative Study of the Histological Structure of Oral Glands on Certain Mammals," to earn her master's degree in 1946.Gretchen Sibley, "A Comparative Study of the Histological Structure of Oral Glands on Certain Mammals" (University of Southern California 1946).
