Both of Kirsten's parents, Marie (1871-1958), called Maja, and Michael (1869-1930), were professional musicians. He was from Hamar, the son of the blacksmith and gunsmith in Strandstuen, and she was from the farm Johnsrud by Dal outside Eidsvoll. Maja Nielsen Johnsrud and Michael Flagstad met in the music community in Kristiania, now Oslo, in the early 1890s and soon became a couple.
Maja came from a very musical family. Already as a little girl she worked as an organist, and from the age of ten she had a permanent job, as she herself has said. Michael came from a family where music did not have such a prominent place as in Maya's case, but a penchant for music had awakened in the boy after his father had given him his violin and taught him to look for melodies on it. Michael was in many ways an artist's soul, a dreamer and an eternal student. He longed for bookish learning and was particularly interested in language, while Maja was outgoing, quick from thought to action, an invaluable quality as a practical musician.
Over the years, Maja became an indispensable orchestral pianist and rehearsal leader for a number of singers and musicians, while Michael sat as a violinist in various theater orchestras and ensembles in the capital. Eventually he advanced to conductor. After the couple's earliest attempts to make a living from music had failed due to poor finances, he trained as a stenographer and had this as a necessary binary in flexible terms in the Norwegian parlament. During this difficult period, they had moved home to his parents in Hamar and that is the explanation why the couples second child were born in Strandstuen in Hamar. She was named Kirsten Malfrid - Kirsten with the beautiful voice - and was baptized in Hamar Cathedral nearby.