Moina, then named Mina, or Minna, was born in Geneva, Switzerland, to an influential Polish-Jewish family from father's and English and Irish from mother's sides, moving to Paris, when she was two years of age.
Her father, Michel Bergson, achieved some musical success in composing the operas Louisa de Montfort and Salvator Rosa.
Her eldest brother, was later Nobel Prize winner Henri Bergson, 1859–1941, joined the faculty of the College of France and is best known for authoring the philosophical work Creative Evolution.
It was also at the Slade in 1882, that Moina met her future friend Annie Horniman, who would become the major financial sponsor for the Matherses, as struggling artists and occultists, in backing the Hermetic Order of the Golden Dawn.
A year later, her future husband founded the Hermetic Order of the Golden Dawn, one of the most influential organisations in the Western Mystery Tradition.