Heredity is the passing of traits to offspring from their parents. This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve. The study of heredity in biology is called genetics, which includes the field of epigenetics. == Overview == In humans, eye color is an example of an inherited characteristic: an individual might inherit the "brown-eye trait" from one of the parents. Inherited traits are controlled by...

Hypochondriasis or hypochondria (sometimes referred to as health phobia or health anxiety) refers to excessive preoccupancy or worry about having a serious illness. This debilitating condition is the result of an inaccurate perception of the condition of body or mind despite the absence of an actual medical condition. An individual suffering from hypochondriasis is known as a hypochondriac. Hypochondriacs become unduly alarmed about any physical or psychological symptoms they detect, no matter how minor the symptom may be, and are convinced that they have, or are about to be diagnosed with, a serious...