Jonker (pronounced yän`ker) grew up with her mother, grandmother and older sister, Anna. Her father, Abraham, never wanted to believe that she was his daughter and that Beatrice (Ingrid’s mother) had had an affair. Unfortunately, Beatrice was fairly unstable emotionally and although she was taken up in a mental institution, she died of cancer when Jonker was 11 years old. At the time, the women had moved from the family farm to Strand and from there to Gordonsbaai, where the girls were attending school. Their father came to fetch them and they had to leave their beloved grandmother behind for a stepmother.
After matriculating at an English high school, Jonker got married to Pieter Venter in 1956. Their daughter, Simone, was born the following year. In 1961 the marriage ended in divorce. By this time Jonker’s debut Ontvlugting had already appeared in print. In 1963 Rook en Oker appeared and she was awarded the Afrikaans Imprint Book Trade prize for it. Jonker used the prize money to travel overseas, but this ended in disaster. She met up with her then-lover, André P. Brink, in Barcelona. By the time they went to Paris, the relationship had become a see-saw of fighting and making up. She ended up at a mental institution there and was sent back to South Africa. Her other lover, Jack Cope, had gotten wind of Brink and didn’t want to pursue his relationship with her any further either.
Jonker couldn’t find work and was even trying to sell the rights of some of her poetry in order to feed herself and Simone. This, in addition to the political turmoil apartheid South Africa was in at the time, added to her emotional distress and she committed suicide by drowning in the ocean at Three Anchor Bay.
Jack Cope was instrumental in having the remainder of her poetry published as Kantelson in 1966. Other than a couple of short stories, Jonker was also the author of a drama entitled Seun na my hart.