Born in 1751 Sosnowska was a Polish noblewoman, who was the daughter of Józef Sosnowski the Field Lithuanian Hetman and one of the richest men in Poland.

[1][2] As a young woman, Sosnowska had an affair with Tadeusz Kościuszko, who at the time was working as her tutor.

[3][4] Whilst she was Kościuszko's pupil Sosnowska and her sister made the first translation from French to Polish of a work on physiocracy.

[7] Due to financial problems, her husband in 1794 transferred her pledged property in Rivne, which she got out of debt.

[9] Historian Halina Filipowicz suggested that the focus on this heterosexual affair by biographers could have been used as a device to hide homosexual inclinations.