We investigate Grade 10 learners' mathematical identities, with a focus on influences on the learners' identities. A mathematical identity questionnaire was given to learners and their test scores accessed. Four learners were purposively selected for interviews on the basis of interesting relationships between their questionnaire responses and test scores. The interview data were analysed for stories of the learners' confidence, beliefs and persistence with mathematics, as indicators of mathematical identity. The findings showed that learners can hold largely robust, modest or largely fragile mathematical identities, which are related to these three indicators. Past and present mathematical experiences, what family members and peers said about the learners and about mathematics, including peer labelling, were related to the learners' identities. Career opportunities associated with mathematics, pleasing others and gaining prestige contributed to how learners formed their mathematical identities.