what test are given to find out why some one might have Epilepsy?

I have a 2 year old step-son , and I can't say this his mother really wants to tell the truth about things that go on in my step-son life,/health.what test are given to find out why some one might have Epilepsy? What dose the test read when a person has Epilepsy? Dose the test say just how the Epilepsye was cause by ?