Twin study finds strong evidence for genetic factors in fainting

The study found both identical twins were almost twice as likely to faint compared to non-identical twins.

Recruited from the Australian Twin Registry, 51 sets of twins of the same gender aged nine to 69 with a history of fainting completed a phone questionnaire.

More than half (57%) reported typical fainting triggers including exposure to blood, injury, medical procedures, prolonged standing, and pain.

Identical twins reported more episodes of fainting and environmental triggers to fainting than fraternal or non-identical twins.

The frequency of fainting in non-twin relatives was low, suggesting