While genes are pivotal in establishing some aspects of emotionality, experience plays a central role in turning genes on and off. DNA is not the hea… - Thomas Lewis

DNA is not the heart’s destiny; the genetic lottery may determine the cards in your deck, but experience deals the hand you can play.

One brain’s blueprint may promote joy more readily than most; in another, pessimism reigns. Whether happiness infuses or eludes a person depends, in part, on the DNA he has chanced to receive.

People rely on intelligence to solve problems, and they are naturally baffled when comprehension proves impotent to effect emotional change. To the neocortical brain, rich in the power of abstractions, understanding makes all the difference, but it doesn’t count for much in the neural systems that evolved before understanding existed. Ideas bounce like so many peas off the sturdy incomprehension of the limbic and reptilian brains. The dogged implicitness of emotional knowledge, its relentless unreasoning force, prevents logic from granting salvation just as it precludes self-help books from helping. The sheer volume and variety of self-help paraphernalia testify at once to the vastness of the appetite they address and their inability to satisfy it.

When people have trouble with their emotions – a bout of anxiety or depression, say, or seasonal gloominess - they often want science to pinpoint an offending neurotransmitter in the way that a witness picks the perp out of a lineup. Is it excessive norepinephrine, too little dopamine, errant estrogen? The answer is apt to dissatisfy: no single suspect can be fingered with confidence because the question itself attributes a fallacious simplicity to the brain.