Drosophila flies began to be used in the study of species evolution during the late 1930s. The geneticists Natasha Sivertzeva-Dobzhansky and Elizabeth Reed pioneered this work in the United States, and María Monclús conducted similar studies in Spain. The research they carried out with their husbands enabled Drosophila population genetics to take off and reveals a genealogy of women geneticists grounded in mutual inspiration. Their work also shows that women were present in population genetics from the beginning, although their contributions have previously remained unacknowledged. The similarities between their research biographies also illustrate their position in a genealogy of partnerships working on Drosophila genetics.