Gloria S. Greenberg was born in Brooklyn, New York on February 15, 1926 to Isaac (Izzy) and Sophie Greenberg. She spent her early childhood at the height of the Great Depression, but Izzy, an enterprising Russian immigrant, managed to keep his family fed and clothed, even arranging music lessons for both his children. 

Gloria began studying piano at age 5 and practiced 6-8 hours a day, despite her parents begging her to go outside and play.  She spent summers in the Borscht Belt singing and accompanying herself on popular songs. However, her deepest love was classical music.  At age 11 she won a gold metal at an Amateur Musicians Contest from New York City Department of Parks .

Gloria’s younger brother Harold began studying violin with Nathan Hieger, a brilliant young student of Reuven Heifetz (father of world-famous violinist Jascha Heifetz). Gloria’s father Isaac became so enamored of Nathan that he arranged an introduction to his precocious daughter. He brought Gloria to Nathan’s family home and asked her to play something. She spun off the Mendelssohn Concerto in G Minor without effort. Nathan then asked Gloria if she knew Beethoven’s C Minor Piano and Violin Sonata. “No,” she replied, “but I’ll sight-read it.” After they played the piece, he was so stunned that she could sight-read so flawlessly that he kissed her on the cheek impulsively. Gloria and Nathan continued meeting at their respective family homes to play violin and piano sonatas together. One afternoon, after playing the 2nd movement of the Bach Concerto for Violin in E Major, they exchanged their first grown-up kiss.

During her teens, Gloria worked at Juilliard School as an accompanist, hoping to earn a full scholarship after high school. After graduating high school, she continued piano studies and taught privately, while preparing a concert-length program of solo piano works. At 19, on October 7, 1945, Gloria gave her debut recital at New York Times Hall (now the Hayes Theater) to favorable notice. The New York Times declared she “showed much promise of fine things to come” and “revealed unusual natural talent.” The Jewish Journal reported that she played Chopin pieces “with the poetry inherent in them and with the eloquence that they possess.”

During the early 40s, the Nazi regime took hold in Europe, making American Jews very anxious. Many had left relatives behind in the “old country.” Nathan enlisted in the Army, carrying his violin from Italy to Algiers during two tours of duty over the course of four years. Gloria was constantly worried for his safety. The two corresponded during his service, and even though he was concerned about their age difference, things were getting more serious between them. 

When Nathan returned from active duty in 1945, he procured a seat in the Baltimore Symphony Orchestra. Following a short engagement, Gloria and Nathan were married on March 31, 1945 in New York City.

A few years before the birth of their first child Joanie in 1949, Nathan was hired by Maestro Fritz Reiner and the Pittsburgh Symphony. The Hiegers relocated to Pittsburgh. While a young mother, Gloria continued to distinguish herself as a professional musician in the burgeoning environment of Pittsburgh. She served as staff pianist for the Pittsburgh Symphony and as accompanist for the then-fledgling Pittsburgh Opera company, playing for such productions as Puccini's Madama Butterfly, Gian Carlo Menotti's Amahl and the Night Visitors, and Kurt Weill's Down in the Valley, as well as co-hosting string quartet evenings in her home.  She was featured in Ralph Lewando’s regular column, “Who’s Who in Pittsburgh Musical Circles” in The Pittsburgh Press, January 9, 1949.