Neonatal severe hyperparathyroidism is a rare condition that presents as striking hyperparathyroidism, hypercalcaemia, and metabolic bone disease. The aetiology needs to be determined soon after diagnosis to direct appropriate management and to determine an accurate prognosis. Taking a family history is a valuable clinical tool in paediatric medicine. Presented here is the case of a neonate presenting with severe hyperparathyroidism. Obtaining the family history, coupled with basic parental studies, enabled a rapid aetiological diagnosis, which allowed for conservative management.