There’s often a blurred line between atypical personality traits and mental illness. Not everyone who frequently fidgets has ADHD, and not everyone who is subdued and withdrawn is depressed. The crucial factor is the degree of suffering for the individual or how their behavior affects others. In Good Shape highlights the diversity of the human brain with striking examples: people with extraordinary memory, individuals with prosopagnosia who cannot recognize faces, and people with synesthesia who can taste numbers or see sounds.