Can you get epilepsy for no reason?

Unfortunately Yes: With the exception of very young children and the elderly, the cause of a seizure is usually not identifiable. In about seven out of ten people with epilepsy (repeated unprovoked seizures), no cause can be found.

Probably not: There is often an identifiable cause: stroke, brain tumor, brain abscess, encephalitis, genetics, cortical dysplasia (abnormally developed cells), or significant brain trauma. Others may not have any of these, but there is still an abnormality on the cellular level that will cause the seizure.

Yes: In many cases, no cause for the seizures can be found. The abnormal bursts of electrical activity in the brain occur for no known reason. It is unclear why they start, or continue to occur. Hereditary (genetic) factors may play a part in some cases. People with idiopathic epilepsy usually have no other brain (neurological) condition. http://patient.info/health/epilepsy-a-general-introduction