GoKawiilBrain Perception Aphantasia Most people see a picture in their mind when they think of a friend's face. People with aphantasia see only a faint image or none. About 4 in 100 people are like this, and about 1 in 100 see nothing at all. A few people have images almost as vivid as real sight. About 1% have no mental images. About 4% have faint or none.
Bones Variation Camptodactyly A finger that stays bent forward at its middle joint and cannot fully straighten, usually the little finger. Under 1% of people have it. Mild cases rarely cause trouble, but the bend can get worse while a child grows. Under 1% of people
Muscle Variation Linburg–Comstock variation An extra tendon link in the forearm that ties the thumb to the index finger. When the thumb bends into the palm, the index fingertip bends with it. Roughly 1 in 5 people have it, but counts vary widely. About 1 in 5 people. Studies range from 5% to 60%.
Heart Reflex Oculocardiac reflex Pressure on the eyeball, or a pull on an eye muscle, makes the heart slow down. It matters most during eye surgery, especially in children. It is not a safe way to slow your own heart. Everyone has the reflex. Its strength varies a lot.
Muscle Involuntary Proctalgia fugax A sudden, cramping pain deep in the rectum that lasts seconds to minutes and then goes away completely. It has no known cause, and it is harmless. About 7% of adults. Studies range from 4% to 18%.