What makes a genius? Even experts argue over whether IQ, EQ, executive function, and/or academic achievement matters most. Nature? Nurture? The role of genetics in intelligence—i.e., the extent to which our smarts are inherited—has long been an academic war zone. What can raise your child’s chances? Cello lessons, French lessons, and juggling.

1. Thirty percent of children under the age of 2 have television sets in their bedrooms.

And 59 percent of under-2s watch two hours of TV every day. The American Academy of Pediatrics recently issued a warning urging parents not to let infants and toddlers watch TV. Giving tiny viewers no known benefits, TV impairs cognitive skills and wastes crucial brain-development time that should be spent conversing with real people, says infant-language expert Roberta Golinkoff, coauthor of Einstein Never Used Flashcards: How Our Children Really Learn—And Why They Need to Play More and Memorize Less. “Language is crucial to children’s learning, and the language they get from the television is not tailored to their individual needs. It will not answer their questions or follow their leads, which is how you create smart kids.”

Elizabeth A. Vandewater, et al. “Digital Childhood: Electronic Media and Technology Use Among Infants, Toddlers, and Preschoolers.” Pediatrics, 119 (5), 1006-15.

2. Six-year-olds who were breastfed consistently as babies score 5 percent higher on IQ tests than their 6-year-old peers who were not.

This stat is based on a study that followed two groups of new Belarusian mothers and their children. One group of mothers breastfed their babies more exclusively (giving them no other food or liquid but breast milk) and for longer (up to a year) than the other group, which breastfed less exclusively and for shorter durations. The children in the first group scored higher in reading, writing, and mathematics. “The first thing a woman can do to raise a smart child is to breastfeed,” says geneticist Ricki Lewis, author of The Forever Fix: Gene Therapy and the Boy Who Saved It. “Human milk has a greater percentage of fat than cow’s milk, needed to insulate our abundant brain cells; a calf needs the protein in its milk for fast growth.”

Michael S. Kramer, et al. “Breastfeeding and Child Cognitive Development.” Archives of General Psychiatry, 65 (5), 578-584.

3. Children who play the piano or a stringed instrument score 15 percent higher on verbal skills than children who don’t play an instrument.

The study that yielded this stat involved students from Boston-area music and public schools; their average age was 10, and the musicians among them had studied music for at least three years. As the authors point out, many previous studies show correlations between musical skills, language skills, and IQ. The question of causality remains: are smart kids good at music, and/or does music make you smart? “The idea that our genes control our fates is called genetic determinism,” Lewis says. “We geneticists fight this idea all the time.”

Marie Forgeard, et al. “Practicing a Musical Instrument in Childhood Is Associated with Enhanced Verbal Ability and Nonverbal Reasoning.” PLoS ONE, 3 (10).

4. Children who are able to delay gratification 15 times as long as their more impatient peers score 210 points higher on their SATs.

In one famous study, children were told they could eat two cookies if they delayed eating the first one. Those who could wait 15 minutes before eating the first cookie scored 210 points higher on their SATs than those who couldn’t wait more than one minute. Impulse control is a crucial factor in executive function. “Scientists know now that being a brainiac is not so much about IQ but about executive function,” Golinkoff asserts. “The ability to switch between tasks, hold things in your working memory, and inhibit impulses is much more connected with success than IQ.”

John Medina. Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five. Seattle: Pear Press, 2010.

5. A child who is raised in a home containing at least 500 books is 36 percent more likely to graduate from high school and 19 percent more likely to graduate from college than an otherwise similar child raised in a home containing few or no books.

Granted, this study was published in 2007, when books were still tangible objects. The gap widens exponentially when the children’s parents are barely literate. “Success in school depends on more than just native intelligence. It also requires a good work ethic,” says psychologist Eileen Kennedy-Moore, author of Smart Parenting for Smart Kids. “Children learn more from what we do than from what we say. Parents who love to read demonstrate to their children that reading is interesting, enjoyable, and worthwhile.”

M.D.R. Evans, et al. “Family Scholarly Culture and Educational Success.” Research in Social Stratification and Mobility, 28 (2), 171-197.

6. The children of women who used cocaine while pregnant are nearly five times as likely to be developmentally disabled as children in the general population.

Fourteen percent of children whose mothers used cocaine while pregnant have IQs below 70, according to a study published in the Journal of the American Medical Association. And 38 percent of children whose mothers used cocaine while pregnant are developmentally delayed. Want valedictorians? Crack is wack.

L.T. Singer, et al. “Cognitive and Motor Outcomes of Cocaine-Exposed Infants.” Journal of the American Medical Association, 287, 1952-1960.

7. Overweight children score 11 percent lower on national reading tests than regular-weight children.

The Temple University scientists whose study includes this stat also found that overweight middle-schoolers had lower GPAs than their regular-weight peers, as well as worse school attendance, more detentions, and more tardiness. This study associates higher body mass with lower scholastic achievement. “Being sedentary has huge opportunity costs for children,” Golinkoff says. “If they’re watching TV or playing computer games, they’re not interacting—and many of the things that make us ‘smart’ are things learned only in the nexus of social interaction.”

Stuart Shore, et al. “Decreased Scholastic Achievement in Overweight Middle School Students.” Obesity, 16 (7), 1535-1538.

8. Aerobic exercise increases children’s executive-functioning abilities by as much as 100 percent.

“The best results accrue, by the way, if you do the exercises with your children,” writes molecular biologist John Medina in his book Brain Rules for Baby, which cites this statistic. “Encouraging an active lifestyle is one of the best gifts you can give your child. It may mean putting away World of Warcraft.” In the same vein, Lewis advises parents: “Focus on what you can control: the environment ... There’s a lot people can do to help their kids. It is what happens after you are born that’s important, not what you inherit.”

John Medina. Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five. Seattle: Pear Press, 2010.

9. People who attended preschool are 52 percent more likely to graduate from high school than people who didn’t attend preschool.

The study that yielded this stat followed two groups of disadvantaged Michigan children from toddlerhood to age 40. One group attended a “high-quality” preschool program at ages 3 and 4; the other never attended preschool. By age 27, five times as many in the preschool group owned their own homes as those in the non-preschool group. By age 40, the non-preschoolers had been arrested on drug charges eight times as frequently as the preschool alumni, and twice as often for physical assault.

L. J. Schweinhart, et al. “Lifetime Effects: The HighScope Perry Preschool Study Through Age 40.” Monographs of the HighScope Educational Research Foundation, 14.

10. Children born to 20-year-old fathers score 3 to 6 points higher on IQ tests than children born to fathers twice that old.

“Advanced paternal age is associated with an increased risk of neurodevelopmental disorders such as autism and schizophrenia, as well as with dyslexia and reduced intelligence,” write the scholars whose study included this figure. “The offspring of older fathers show subtle impairments on tests of neurocognitive ability.” The modern tendency to delay fatherhood might be cause for concern, the scholars suggest.

S. Saha, et al. “Advanced Paternal Age Is Associated With Impaired Neurocognitive Outcomes During Infancy and Childhood.” PLoS Medicine, 6 (3).

11. Learning to juggle can increase the volume of gray matter in children’s brains by 3 percent.

Brain structure is largely determined by genes, but not entirely. “Learning a difficult perceptual-motor skill—juggling—induced a 3 percent increase in the volume of gray matter in visual attention areas,” write the Yale scholars whose report cites this figure. The volume of gray matter in the brain’s frontal region is linked with general cognitive ability, the scholars avow.

Jeremy Gray and Paul Thompson. “Neurobiology of Intelligence: Science and Ethics.” Nature Reviews Neuroscience, 5, 471-482.

12. Children in welfare-recipient families hear nearly four times fewer words per year than children in professional-class families.

The more words we hear, the bigger our vocabularies and the higher our academic achievement, according to the scholars whose research revealed that children in welfare families hear about 3 million words per year, while children in working-class families hear 6 million and children in professional-class families hear 11 million. (That boils down to 616 and 1,251 and 2,153 per day, respectively.) According to the study, welfare-recipient children know 500 words by age 3, compared with 750 and 1,100 in the other groups.

Todd R. Risley and Betty Hart. Meaningful Differences in the Everyday Experience of Young American Children. Baltimore: Brookes Publishing, 1995.

13. Kids who have studied a foreign language for two years have SAT scores 14 percent higher than those of kids who never studied foreign languages.

One year of foreign-language study was linked with slightly higher SAT scores, but two years yielded increases of 14 and 13 percent on the test’s verbal and math portions, respectively, over the scores of students who had never studied foreign languages. Each additional year of foreign-language study yielded further increases. “The verbal scores of students who had taken four or five years of foreign language were higher than the verbal scores of students who had taken four or five years of any other subject,” write the scholars whose research yielded this stat. Vive les conjugaisons.

Thomas C. Cooper. “Foreign-Language Study and SAT-Verbal Scores.” Modern Language Journal, 71 (4), 381-387.

14. Students who spend more than two hours a day playing computer and video games score 9.4 percent lower on school exams than students who play no such games.

The effects of electronic game-playing on academic achievement spark intense debate. A study conducted on students in the U.K. compared the test results of frequent gamers with those of nongamers. “Not a single significant positive correlation was found between gaming frequency and academic performance,” the researchers write. “Excessive videogame playing—like excessive anything—can interfere with schoolwork as well as reading for pleasure, playing outside, sleeping, or interacting directly with friends and families,” says Kennedy-Moore.

Barry Ip, et al. “Gaming Frequency and Academic Performance.” Australasian Journal of Educational Technology, 24 (4), 355-373.

15. The children of mothers who were exposed to pesticides while pregnant have 1.4 percent lower IQs per increment of exposure than children whose mothers were not exposed to pesticides.

Columbia University scientists studied 7-year-olds and their mothers, finding direct links between prenatal exposure to the common agricultural pesticide chlorpyrifos and lower IQs. The negative impact of pesticide exposure is even greater on working memory, one element of those crucial skills collectively called “executive function.” The notion that invisible components of the air we breathe might lower our children’s intelligence is daunting indeed.

V. Rauh, et al. “Seven-Year Neurodevelopmental Scores and Prenatal Exposure to Chlorpyrifos.” Environmental Health Perspectives, 119 (8).