Epilepsy can be inherited from a mother, and children of mothers with epilepsy face a somewhat higher risk than children of fathers with the condition. A large cohort study found that the 30-year cumulative risk of developing epilepsy is about 8.1% for children of affected mothers, compared to 5.3% for children of affected fathers and 2.1% for children of unaffected parents. That means the vast majority of children born to mothers with epilepsy will never develop it, but the risk is real and measurably greater when the affected parent is the mother.
How Much Higher Is the Risk From a Mother?
The roughly 45% greater risk from a mother compared to a father has been observed across multiple studies and is sometimes called the “maternal effect.” A population-based study published in Annals of Clinical and Translational Neurology found that the incidence rate of epilepsy in children of affected mothers was 260 per 100,000 person-years, versus 172 per 100,000 for children of affected fathers. Both figures are elevated compared to the baseline rate of about 79 per 100,000 for children with no parental history of epilepsy.
Interestingly, not all research agrees on how strong this maternal effect is. A study published in the Annals of Neurology that focused specifically on families with multiple epilepsy cases found no difference in epilepsy rates between children of affected mothers and affected fathers. The researchers suggested that earlier studies showing a maternal effect may have been influenced by other factors, like the type of epilepsy or how cases were identified. So while the maternal effect appears in large population data, it may not apply equally to every family or every epilepsy type.
Why Mothers May Pass on Higher Risk
Several biological mechanisms could explain why maternal inheritance carries a greater risk. One is mitochondrial DNA, the small set of genes inside your cells’ energy-producing structures. Mitochondrial DNA is inherited exclusively from the mother. Mutations in these genes can cause specific epilepsy syndromes, including MERRF (a condition involving seizures, muscle jerks, and progressive neurological problems) and maternally inherited Leigh syndrome, a severe disorder that affects the brain and nervous system. These conditions are rare, but they illustrate a pathway through which epilepsy risk travels strictly through the maternal line.
Beyond mitochondrial DNA, the prenatal environment itself may play a role. A developing baby is exposed to the mother’s physiology for nine months. Factors like seizure activity during pregnancy, anti-seizure medications, and hormonal changes could all influence brain development in ways that affect seizure susceptibility later. This makes it difficult to separate purely genetic inheritance from the effects of the shared prenatal environment.
There’s also the possibility of genetic mosaicism, where a mother carries a mutation in only some of her cells. In one documented case, two half-sisters both developed Dravet syndrome, a severe childhood epilepsy caused by mutations in the SCN1A gene. Their mother had never experienced seizures and standard genetic testing didn’t detect the mutation in her blood. Only deeper analysis revealed she carried the mutation in a fraction of her cells. This kind of hidden mosaicism means a mother can pass on an epilepsy-causing gene even when she has no personal history of seizures.
The Type of Epilepsy Matters
Not all forms of epilepsy carry the same hereditary risk. Genetic factors play some role in an estimated 70 to 80% of epilepsy cases, but the degree of heritability varies enormously depending on the type. The remaining 20 to 30% of cases have a clearly acquired cause, such as a brain injury, stroke, or tumor, and these forms are not inherited.
Generalized epilepsies, the types that affect both sides of the brain from the start, tend to have the strongest genetic component. Data from the American Epilepsy Society estimates that siblings and offspring of people with idiopathic generalized epilepsy have about an 8.2% risk of developing epilepsy themselves. For childhood absence epilepsy specifically, research has found that the mother’s brain wave patterns on an EEG are the strongest predictor of seizure risk in her other children, again pointing to a maternal influence in transmission.
Focal epilepsies, which originate in one area of the brain, generally carry a lower hereditary risk, though genetic contributions still exist. If your mother has focal epilepsy caused by a known structural problem, like a scar from a head injury, the chance of you inheriting epilepsy from her is minimal. If her epilepsy has no identified structural cause, a genetic contribution becomes more likely.
What “Hereditary” Actually Means Here
When people ask whether epilepsy is hereditary, they often imagine a single gene being passed from parent to child, like the pattern for conditions such as sickle cell disease. Epilepsy rarely works that way. Most common forms of epilepsy involve multiple genes, each contributing a small amount of risk, interacting with environmental factors. You don’t inherit epilepsy itself so much as a threshold for seizure susceptibility.
A few rare epilepsy syndromes do follow more predictable inheritance patterns. Dravet syndrome, caused by SCN1A mutations, can be passed directly from parent to child, though most cases arise from new mutations that weren’t present in either parent. The mitochondrial syndromes mentioned earlier follow strict maternal inheritance. But these account for a small fraction of all epilepsy cases.
For the majority of people, having a mother with epilepsy raises your risk from a baseline of about 2% to roughly 8%. That’s a meaningful increase in relative terms, but it still means there’s a greater than 90% chance you won’t develop the condition.
Genetic Testing and Family Planning
If you have epilepsy and are thinking about having children, or if your mother has epilepsy and you want to understand your own risk, genetic testing can sometimes provide clarity. Current guidelines strongly recommend that anyone with unexplained epilepsy, meaning epilepsy without an obvious structural, infectious, or metabolic cause, be offered comprehensive genetic testing. This typically involves multi-gene panels or whole-genome sequencing that can identify known epilepsy-related mutations.
Genetic counselors can help interpret results and put risk numbers into context for your specific situation. The type of epilepsy, the number of affected family members, and whether a specific genetic mutation has been identified all change the calculation. A woman with idiopathic generalized epilepsy and an affected parent faces a different risk profile than a woman whose epilepsy followed a head injury. These are distinctions that generic risk percentages can’t capture, which is why individualized counseling is valuable for anyone making decisions about family planning.