We love strange psychological disorders here at mental_floss. Refer to past blogs regarding Proprioception Deficit Disorder and extreme narcissism, among others. But this one may take the cake: a disorder known as prosopagnosia, otherwise known as face blindness.
Prosopagnosians find faces indistinguishable from one another, and even after talking to someone intimately for hours, likely will not remember them they next time they meet. It can be a very sad state of affairs: parents who are unable to pick out which Kindergartener is theirs; sufferers who, according to the New York Times, "become shut-ins, overwhelmed by a world of blank faces." (Nicely poetic, Times.) Also according to that paper of record, the disease is considerably more prevalent than we think: up to 2.5% of the population suffers from it to one degree or another. "Before their diagnosis, many people with prosopagnosia assume that they are just socially awkward. 'You have a perceptual problem, and you self-ascribe,' says Dr. Ken Nakayama, a prosopagnosia researcher. 'You say you are an introvert.'"
Unless this is another effort by Big Pharma to convince us that we suffer from some newly-described malady and then sell us its miracle cure in pill form, I find these statistics a little frightening. But they would explain a lot -- the absent-minded cousin who can never remember your name; the shy kid who never introduces himself for fear that he already has. Anyone out there in blog-world know a sufferer?