Are vasovagal reactions hereditary?

Nobody knows for sure, but they seem to be. The vasovagal fainting reaction to seeing needles and blood IS genetic. Although most specific phobias stem from the individual themselves, the most common type of trypanophobia, affecting 50% of trypanophobes, is an inherited reflex. Approximately 80% of trypanophobes report that a relative within the first degree exhibits the same disorder.