Katarina's father Sune Folkesson was Lord of Ymseborg, lawspeaker of Västergötland, and in some literature he is referred to as Earl of the Swedish.

Young Erik was, according to semi-legendary material, physically lame and spoke with a stutter ("läspe och halte"), and he was reportedly of a kindly nature.

Katarina had received an immense dower upon the marriage: some legends speak romantically about "half the kingdom".

Because Scandinavian customary law dictated that no clan property could be held by a member of a religious order, she transferred some lands, including her queenly dower, to certain relatives and gave others as donations to ecclesiastical institutions.

Since she immediately devoted herself to a sequestered religious life and not to family at Erik's death, the conclusion has tended to be that they did not have any surviving children.