As quoted from Dr. Dean K. Naritoku of the Epilepsy Center at SIU (Southern Illinois University)
"There is no doubt that at least some of the epilepsies are genetically related, i.e., related to heredity. Most of the generalized epilepsy syndromes such as childhood absence, Juvenile Myoclonic Epilepsy and tonic-clonic seizures on awakening) as well as some partial epilepsy syndromes (such as Benign Rolandic Epilepsy) are felt to be genetic in cause, Some genetic markers (gene locations) have even been discovered over the last few years. Some examples include gene markers for Juvenile Myoclonic Epilepsy, Benign Neonatal Convulsions, and Seizures with Auditory components. However, just because someone has the gene does not automatically mean they will develop epilepsy. Even identical twins, who have the same genetic material, do not always have epilepsy in both sibling despite the fact that one has a "genetic" epilepsy. Thus, genetic makeup strongly predisposes persons to epilepsy, but is not the only factor that causes it."
Interesting stuff.. great topic!