Most of us not gifted with an Einstein-size brain or extreme self-confidence have sometimes wondered: Am I really smart enough to achieve my dreams? Some of us have even turned down an offer or not pursued an opportunity because we're afraid we simply don't have the mental horsepower to succeed.

That's a shame, suggests fascinating new science conducted by Nobel laureate James Heckman and colleagues, because IQ has pretty much nothing to do with success.

Personality trumps smarts

To come to that conclusion, the researchers combed through data on IQ scores, standardized test results, grades, and personality assessments for thousands of people in Britain, America, and the Netherlands, according to Bloomberg View's Faye Flam (hat tip to Science of Us for the pointer). They then calculated how closely each of these factors predicted future earnings.

What percentage of future success depended on a person's IQ? (And yes, before I get angry tweets and comments, I understand "success" isn't just about money, but that's the measurable outcome these scientists used as a proxy for the word.) Only a miniscule 1 or 2 percent.

Put in layman's terms, raw IQ scores hardly matter at all when it comes to worldly success. So what characteristics matter more?

Grades were a bit better at pointing to future high earners, but not, the researchers suspect, because of what that A in chemistry says about your brain's innate capacities. Instead, the team concluded that character traits such as conscientiousness (in essence, the fact that you got out your periodic table and studied) and openness (that you were curious about chemistry in the first place) are far more predictive of life outcomes.

"The study found that grades and achievement-test results were markedly better predictors of adult success than raw IQ scores," reports Flam. Why? "Grades reflect not just intelligence but also what Heckman calls 'noncognitive skills,' such as perseverance, good study habits, and the ability to collaborate--in other words, conscientiousness. To a lesser extent, the same is true of test scores."

In short: "Personality counts," according to Flam. Apparently, a lot.

Yes, you can change your personality

That's good news for those interested in self-improvement, because while IQ is largely fixed, personality is more malleable. Other research from Heckman shows that childhood interventions to help kids develop the right personality traits for success can prove helpful. Meanwhile, researchers in other disciplines attest that grit can be taught.

Other psychology experts argue persuasively that personality is not destiny. We do ourselves a disservice, they note, when we see our personality as fixed and inflexible. In fact, science suggests that our character and behavior can be drastically altered by new circumstances or passions.

The bottom line of all this? Stop asking yourself, "Do I have the brains to succeed?" and start asking yourself, "Do I have the character?" instead. And if the answer is "not right now," don't be too discouraged. It is entirely possible to change for the better.