Participants completed computer-assisted telephone interviews on possible risk factors for breast cancer and other conditions. Sister Study investigators were interested in whether early-life exposures affected risk of breast cancer and other health conditions; therefore, the participants also completed a self-administered family history questionnaire including early-life exposures that women could reasonably report retrospectively. A pre-paid phone card was provided to participants to encourage them to contact their mother or other relatives for assistance; however, we do not know whether participants contacted relatives or consulted birth records before completing family history questionnaires.
