Your Brain: The Missing Manual

Nature vs. Nurture

Now that you've journeyed through the stages of life and seen how they shape your brain, there's only one question left. Namely, who should you thank for the undeniable wonderfulness of you?

For centuries, scientists have debated whether innate, inherited qualities (your nature) or personal experiences (the nurture) play the greater role in determining traits like personality and intelligence. The question is at least partly a matter of perspective. For example, if you compare the average person to a tree sloth, it's clear that genetic programming decides whether you're typing in cubicle or lounging in a subtropical tree. On the other hand, if you compare a modern bank teller to an eighth-century Tibetan monk, you might be inclined to think that environment has more than a passing influence on the way you spend your Monday mornings.

When scientists compare the influence of genes versus environment, they have a specific definition in mind. Essentially, the question scientists want to answer is this: if you gather together a large group of people, what accounts for the variation in their abilities? In other words, why can Joe outtalk, outcharm, and outromance Lenny, and why is Joan so much dafter than Sarah? When asked this way, the answer is easier to answer and no less important.

Heritability

To describe how strongly a specific characteristic depends on your genetic makeup, scientists use a measurement called heritability, which ranges from 0 to 1.

A heritability of ...