Fear of Heights
Based on your genetics and other factors, you have a ??% chance of being afraid of heights.
Heights and balance
While standing upright, the brain uses visual input from nearby objects to make tiny postural adjustments that help maintain balance. However, when standing at a high elevation relative to their surroundings — like at the edge of a tall building — most people feel somewhat off balance. This is because visual input from nearby objects is lacking, and the objects in view are too far away for the brain to use for balance control.
Fear of heights
Some scientists believe that people with an extreme fear of heights may depend more heavily on visual input for balance control than other people who can use physical sensations as well as visual input to keep their balance. As a result, they may feel especially unstable when standing at an elevation, triggering a fear response.