Sonja Anita Maria Bernadotte, née Haunz, was born in Konstanz on Lake Constance in southern Germany. Both of her parents worked on the Mainau island estate, a major tourist attraction on Lake Constance that features elaborate flower gardens and a butterfly house. She attended a home economics school, worked in nature conservation and landscaping in Bad Godesberg, and as a hotel clerk in the English coastal town of Margate. She then returned to work on the Mainau estate. In 1972, she married as his second wife Count Lennart Bernadotte of Wisborg, a descendant of the Swedish royal family, whom she had met while working as his personal assistant. The couple had five children. Her husband bought Mainau and she eventually became its manager. After her husband's death, Countess Sonja Bernadotte became head of the foundation that organizes the annual Nobel Laureate Meetings at Lindau.