The main cause of sudden epilepsy symptoms in a three-year-old child is genetic factors, while other causes include intracranial infections, intracranial tumors, intracranial hemorrhage, and craniocerebral trauma. 1. Genetic factors: genetic background is an important factor that leads to epilepsy in children, if there is an epileptic parent or a genetic history of epilepsy in the family, the child is more likely to develop epilepsy. 2. Intracranial infections: Intracranial infections caused by bacteria, viruses, mycoplasma and other pathogens can also lead to epilepsy symptoms, such as septic meningoencephalitis, viral encephalitis, mycoplasma encephalitis and so on. 3. Intracranial tumors: intracranial tumors compress brain tissue, causing local electrophysiological disorders and epilepsy. 4. Intracranial hemorrhage: the gradual formation of softened foci after intracranial hemorrhage may lead to abnormal cerebral neuron discharges, followed by epilepsy. 5. Craniocerebral trauma: Craniocerebral trauma may cause intracranial hemorrhage, skull fracture, brain damage, and then epilepsy. In short, there are many causes of epilepsy in children, and it is recommended to consult a pediatrician in a timely manner to clarify the cause of the disease and take targeted treatment.