Not everyone has epilepsy, but epilepsy is not the only thing that causes seizures either. For instance, illness with high fevers can cause seizures in otherwise healthy people. I have an aunt with epilepsy and no one else in my family has it, but my Dad had one due to medication interactions after having a stroke and a niece who had one because she had a 107 degree fever when she had meningitis as a child.
You have to be born with a brain "disorder" to have an epileptic seizure. But there are somethings that can cause an average person to have a non-epileptic seizure (mostly caused by flashing, different color lights). I have epilepsy, so I know quite a few things.
Everyone can have a seizure. Not everyone has epilepsy. Epilepsy is when you have multiple seizures through out your life. The types of seizures are grand mal, the worst, abscence, atonic, myoclonic, simple partial, complex partial, gelastic seizures, dacrystic seizures, non epileptic seizures, and status epilepticus. Hope this helpled