This means that people who are closely related may have a similar tendency to faint, Berkovic said. But keep in mind that the study has several weaknesses. This was a small study, and the researchers did not perform diagnostic tests to exclude other causes of fainting, such as heart problems and autonomic failure.

The research could help scientists identify the genes underlying a tendency to faint, Berkovic said.

To further explore this topic, there should be genetic studies on large families examining the tendency to faint, he said.