Anni-Frid was born illegitimately in Ballangen, near Narvik, Norway during the Nazi occupation as a result of a liaison between Synni - her mother - and a married German sergeant, Alfred Haase. She was unknowingly part of the Nazi Lebensborn plan to expand the Aryan race. Anni-Frid believed that her father had died when his ship to Germany was sunk during the war. After a German magazine published the story of her origins in 1977, Anni-Frid discovered that her father had not died, and was able to meet him.
At the end of World War II Anni-Frid, her mother and grandmother fled to Sweden for fear of reprisals from the Norwegian population - whose government put many German-fathered children into mental institutions, or sent them overseas. Synni died before Anni-Frid was two, so she was brought up by her grandmother in Eskilstuna, Sweden.
Anni-Frid got her first job as a jazz singer at the age of 13, then formed her own band, the Anni-Frid Four, marrying the bass player Ragnar Fredriksson at age 18, with whom she had two children before divorcing.
In 1967 Anni-Frid won a TV talent contest, and made an album for EMI. She made a second in 1971, produced by Benny Andersson, laying the foundations for ABBA. She married Benny on October 6, 1978 - divorcing in 1981.
In 1992 Anni-Frid married Heinrich Ruzzo Reuss (1950-1999), of the Princely Reuss family.