“Does it run in families” is usually one of the first questions that comes up after a diagnosis, and the honest answer is: sometimes, but it’s a lot more complicated than a simple yes or no. Genetics is genuinely one of the major causes of epilepsy, estimates put it somewhere between 30 and 70 percent of cases depending on how broadly “genetic” is defined, but that doesn’t mean epilepsy works like eye color, passed down in a predictable, guaranteed way. It’s closer to a risk that gets inherited than a fixed outcome that does.
The mechanism itself comes down to genes that control how neurons communicate with each other. A lot of these genes code for ion channels, the tiny structures in nerve cell membranes that manage the flow of charged particles like sodium and potassium, which is exactly what generates the electrical signals neurons use to fire. One of the most studied examples is a gene called SCN1A, which codes for a sodium channel involved in nerve signaling. Mutations in this single gene are linked to a range of conditions, from relatively mild seizures with fever in early childhood to Dravet syndrome, a severe and treatment-resistant form of epilepsy. Interestingly, around 90 percent of SCN1A mutations found in children with Dravet syndrome aren’t inherited from either parent at all. They’re new mutations, called de novo mutations, that arise spontaneously in the egg or sperm before conception. This is one of the most counterintuitive parts of epilepsy genetics: a condition can be entirely genetic in cause while having no family history behind it whatsoever.
That distinction matters a lot, because it splits genetic epilepsy into two very different categories. One is inherited, meaning a parent actually carries and passes down the relevant gene variant, and this tends to show up as a pattern across multiple family members over generations. The other is spontaneous, where the mutation appears for the first time in that specific child, with no trace of it in either parent’s DNA. Genetic causes are actually more common in children who develop severe, treatment-resistant epilepsy very early in life, and in those cases, a family history is often completely absent, since the mutation simply wasn’t there in the parents to begin with.
For most types of epilepsy, though, it isn’t about a single gene misfiring in isolation. Research increasingly points toward what’s called a polygenic pattern, meaning multiple genes, each contributing a small piece of overall risk, combine together, sometimes alongside environmental factors like brain injury or infection, to push someone over the threshold into having seizures. Generalized epilepsies, especially syndromes like juvenile myoclonic epilepsy, tend to show a particularly strong genetic component, with shared genetic influence estimated as high as 90 percent in some analyses. Focal epilepsies, by contrast, tend to have a much more varied and less clearly defined genetic signature. A landmark 2023 genetic study compared DNA from nearly 30,000 people with epilepsy against more than 52,000 people without it, representing the largest study of its kind to date, and continues to be a major source of new findings about exactly which combinations of genes are involved.
So what does this actually mean for someone with a family member who has epilepsy? The honest numbers are reassuring more often than they’re alarming. About one in three people with epilepsy do have a family member with the condition, and first-degree relatives of someone with inherited epilepsy face roughly a two- to four-fold increase in risk compared to the general population. That sounds significant until it’s put next to the baseline: the general risk of developing epilepsy by age 20 is around 1 in 100, so even a four-fold increase generally lands somewhere around 2 to 5 in 100. Most parents with epilepsy do not have children who develop it. Most siblings of someone with epilepsy do not develop it either. Risk isn’t destiny here, and having relevant genes doesn’t guarantee seizures will ever actually happen, since plenty of people carry a gene variant associated with epilepsy and never develop symptoms at all.
Genetic testing has become a real, practical tool in this picture rather than just a research curiosity. For people with epilepsy, particularly when seizures are severe, treatment-resistant, or start very early in life, testing a blood or saliva sample can sometimes identify the specific genetic cause behind it. That answer can directly shape treatment, since some genetic epilepsy syndromes respond better to certain medications than others, and it can also clarify risk for future children or other family members, since a confirmed inherited variant means relatives can be offered testing of their own if they choose.
None of this makes epilepsy simple, and it isn’t meant to. Genetics is a real, well-documented piece of why epilepsy happens, but it’s a piece that works in combination with spontaneous mutation, environmental factors, and a threshold that’s different for every single brain. Knowing a mutation exists still isn’t the same as knowing what it will actually do.
References
University of Chicago Medicine. Causes of epilepsy. Uchicagomedicine.org.
MyEpilepsyTeam. (2026). Can epilepsy be genetic? Inherited genes and 7 other causes. Myepilepsyteam.com.
MyEpilepsyTeam. (2026). Is epilepsy genetic? Understanding how it’s passed on. Myepilepsyteam.com.
Healthline / Medical News Today. (2023). Is epilepsy genetic? Causes, risk factors, and screening. Healthline.com.
Epilepsy Society. Genetics and epilepsy. Epilepsysociety.org.uk.
Epilepsy Foundation. Genetic causes of epilepsy. Epilepsy.com.
Healthmatch. (2022). Can epileptic seizure disorder be inherited from a parent? Healthmatch.io.
Defeating Epilepsy Foundation. (2024). SCN1A genetic mutation and epilepsy. Defeatingepilepsy.org.