Joan Ruth Bader was born on March 15, 1933, at Beth Moses Hospital in Brooklyn, New York City, the second daughter of Celia (née Amster) and Nathan Bader, who lived in the Flatbush neighborhood. Her father was a Jewish emigrant from Odessa, Ukraine, at that time part of the Russian Empire, and her mother was born in New York to parents who came from Kraków, Poland. The Baders' elder daughter Marylin died of meningitis at age six, when Ruth was 14 months old. The family called Joan Ruth "Kiki", a nickname Marylin had given her for being "a kicky baby". When "Kiki" started school, Celia discovered that her daughter's class had several other girls named Joan, so Celia suggested the teacher call her daughter "Ruth" to avoid confusion. :3–4 Although not devout, the Bader family belonged to East Midwood Jewish Center, a Conservative synagogue, where Ruth learned tenets of the Jewish faith and gained familiarity with the Hebrew language. :14–15 Starting as a camper from the age of four, Ruth attended Camp Che-Na-Wah, a Jewish summer program at Lake Balfour near Minerva, New York, where she was later a camp counselor until the age of eighteen.