6. You've used recreational drugs
A 2012 study of more than 6,000 Brits born in 1958 found a link between high IQ in childhood and the use of illegal drugs in adulthood.
"In our large population-based cohort study, IQ at 11 years was associated with a greater likelihood of using selected illegal drugs 31 years later," wrote researchers James W. White, Catharine R. Gale, and David Batty.
They conclude that "in contrast to most studies on the association between childhood IQ and later health," their findings suggest "a high childhood IQ may prompt the adoption of behaviors that are potentially harmful to health (i.e., excess alcohol consumption and drug use) in adulthood."
7. You're lefthanded
More recent research associates left-handedness with "divergent thinking," a form of creativity that allows you to come up with novel ideas from a prompt — at least among men.
The more marked the left-handed preference in a group of males, the better they were at tests of divergent thought.
Left-handers were more adept, for instance, at combining two common objects in novel ways to form a third — for example, using a pole and a tin can to make a birdhouse. They also excelled at grouping lists of words into as many alternate categories as possible.
8. You're tall
A 2008 Princeton study of thousands of people found that taller individuals scored higher on IQ tests as kids and earned more money as adults.
The researchers write: "As early as age 3 — before schooling has had a chance to play a role — and throughout childhood, taller children perform significantly better on cognitive tests."
9. You drink alcohol regularly
Evolutionary psychologist Satoshi Kanazawa and colleagues found that, among Brits as well as Americans, adults who had scored higher on IQ tests when they were kids or teens drank more alcohol, more often in adulthood than those who had scored lower.
10. You learned to read early
In 2012, researchers looked at nearly 2,000 pairs of identical twins in the UK and found that the sibling who had learned to read earlier tended to score higher on tests of cognitive ability.
The study authors suggest that reading from an early age increases both verbal and nonverbal (e.g. reasoning) ability, as opposed to the other way around.
11. You worry a lot
A growing body of research suggests that anxious individuals may be smarter than others in certain ways, according to Slate's coverage of several different studies on anxiety.
In one study, for example, researchers asked 126 undergrads to fill out questionnaires in which they indicated how often they experienced worry. They also indicated how often they engaged in rumination, or thinking continuously about the aspects of situations that upset them, as psychologist Dr. Edward Selby reported in Psychology Today.
Results showed that people who tended to worry and ruminate a lot scored higher on measures of verbal intelligence, while people who didn't do much worrying or ruminating scored higher on tests of nonverbal intelligence.