mine was a birth defect, but my epilepsy remained dormant for a long time, and i no idea i had it until i started having symptoms and couldn't explain what they were until i had my first Grand Mal
there are many causes, i'm not going to list a lot of them, but usually if you actually "have epilepsy" it would be a birth defect, or a serious brain injury, or even possibly something that could be hereditary.
the seizures themselves are caused by abnormal excessive or synchronous neuronal activity (for me)
as for a cure- there isnt really a true cure that has been recognized
some might claim to treat/cure with alternative medicines / therapies such as Craniosacral Therapy
(i have had this done by multiple practitioners over a period of 4+ years in the past, and it didnt seem to help)
if your lucky you might just "grow out" of it at some point as you grow into an adult.
(i have known people with epilepsy who had this happen)
Vagus nerve stimulation
http://en.wikipedia.org/wiki/Vagus_nerve_stimulationthen there is brain surgery, first they have to determine where the seizures are originating from in the brain, and then if it is possible to remove the area in the brain that is causing any problem.
if i find something else i will mention it later.