Long thought to be caused by problems at birth, researchers now say that in most cases cerebral palsy may actually originate in a person’s genes much like other developmental disabilities.

The finding, reported online in the journal The Lancet Neurology in January, comes as cerebral palsy rates have remained steady for over 40 years despite marked progress in medical care during and after birth, the researchers note.

“There is a widespread misconception that most cases of CP are caused by difficult delivery leading to birth asphyxia,” said Andres Moreno De Luca of the Geisinger Health System in Pennsylvania and the lead author of the paper. “What we’re finding is a growing body of evidence that suggests mutations in multiple genes are responsible for CP. In fact, we suspect these genetic abnormalities may also be the cause of some difficult births to begin with.”

Scientists already know of six genes that are associated with cerebral palsy when altered, but Moreno De Luca and his colleagues say that more will likely be identified.

Further understanding of the genetic roots of the disorder could help bring about better therapies for those with cerebral palsy, the researchers said.