IQ tests have been used for over a century to measure cognitive abilities, but intelligence is a complex and often misunderstood trait. Many factors influence IQ, and its relationship with success, mental health, and even physical health continues to be explored. Here are 50 intriguing and surprising facts about IQ and intelligence.
1. Personality Matters More Than IQ for Success
While IQ is often linked to academic and professional success, research suggests that personality traits—such as perseverance, selfdiscipline, and emotional intelligence—are more significant predictors of achievement. People with average IQs but strong work ethics often outperform those with high IQs but poor motivation.
2. The Origin of IQ Tests: Alfred Binet’s Vision
The first practical IQ test was created by French psychologist Alfred Binet in 1905 to help identify children who needed extra educational support. However, Binet strongly opposed the idea that intelligence was fixed and believed it could be developed through education and environment.
3. Money Can Boost IQ Scores
Studies show that offering financial incentives for IQ tests can significantly improve scores. In one experiment, participants offered $10 performed 20 points higher, highlighting the role of motivation in cognitive performance.
4. High IQ and Dark Humor
People with higher IQs tend to have a better appreciation for dark humor. Studies suggest that understanding morbid jokes requires advanced cognitive processing and emotional detachment, which are associated with intelligence.
5. The Flynn Effect: Humans Are Getting Smarter
IQ scores have steadily increased over the past century in a phenomenon known as the “Flynn Effect.” To maintain the average IQ at 100, test difficulty is regularly adjusted. A person who scored 100 a century ago would likely score around 70 today.
6. Iodized Salt Led to a National IQ Boost
The introduction of iodized salt in the U.S. in the 1920s increased national IQ averages by 3.5 points. In regions with severe iodine deficiency, IQ scores increased by as much as 15 points in just a decade.
7. IQ Is Always Relative
IQ scores measure intelligence relative to the general population, not an absolute level of intelligence. If society as a whole becomes smarter or less intelligent, the IQ scale adjusts accordingly.
8. Stephen Hawking on IQ Scores
When asked about his IQ, physicist Stephen Hawking replied, “I have no idea. People who boast about their IQ are losers.” He believed that creativity and curiosity mattered more than raw intelligence.
9. High IQ Doesn’t Prevent Poor Decision making
Having a high IQ doesn’t guarantee good reasoning skills. Many intelligent people suffer from “dysrationalia,” a condition where they make irrational choices due to cognitive biases.
10. Dictators Who Banned IQ Tests
Both Adolf Hitler and Joseph Stalin banned IQ testing in their regimes. Hitler opposed IQ tests for being “too Jewish,” while Stalin rejected them as “bourgeois.”
11. IQ and Forced Sterilization
Until 1977, North Carolina had laws that allowed the forced sterilization of people with IQs below 70, a practice that has since been condemned as unethical.
12. The Man Banned from Sex Due to Low IQ
In 2011, a U.K. court ruled that a man with an IQ of 48 lacked the cognitive ability to understand the risks of sexual activity, leading to a controversial ruling that banned him from having sex.
13. High IQ and Mental Health Risks
Studies show that people with high IQs are more likely to suffer from mental health conditions such as depression, anxiety, ADHD, and bipolar disorder. They also have a higher prevalence of allergies and autoimmune disorders.
14. IQ Minimum for Military Service
The U.S. military requires a minimum IQ of 80 for enlistment. During the Vietnam War, this standard was temporarily lowered, and soldiers with lower IQs suffered five times the casualty rate of their higherIQ counterparts.
15. Tony Hawk: The Skater Genius
Professional skateboarder Tony Hawk has an IQ of 144. Despite being bullied in school for his passion, he became one of the most influential athletes in extreme sports history.
16. Nobel Prize Winner’s Controversial IQ Proposal
Physicist William Shockley, who co-invented the transistor, suggested that people with IQs below 100 should be paid to undergo voluntary sterilization—a highly controversial and widely condemned idea.
17. The Effect of Marijuana on IQ
Frequent marijuana use during adolescence is associated with an average IQ drop of 8 points in adulthood, though the extent of its longterm cognitive effects remains debated.
18. Outdated IQ Terminology
The terms “idiot,” “imbecile,” and “moron” were once official classifications for different IQ ranges. Over time, they became derogatory and were replaced with neutral terminology.
19. Lead Poisoning and IQ Decline
Even though leaded gasoline was banned decades ago, residual lead in the environment continues to lower children’s IQ scores.
20. People with Down Syndrome Can Have High IQs
While Down syndrome is often associated with intellectual disability, some individuals have IQs above 120, demonstrating significant cognitive ability.
21. Francis Galton: The Pioneer of Intelligence Studies
Sir Francis Galton, cousin of Charles Darwin, was a pioneer in intelligence studies. He introduced concepts such as “nature vs. nurture” and developed fingerprint analysis, meteorology, and the dog whistle.
22. Group Settings Lower IQ Performance
Being in a group can temporarily lower IQ due to social conformity and reduced individual critical thinking.
23. Some Police Forces Reject Applicants with High IQs
Some police departments, including in New York, have rejected applicants with exceptionally high IQs, arguing they might become bored with routine police work.
24. Nazi War Criminals Had High IQs
Psychological tests conducted at the Nuremberg Trials revealed that many Nazi war criminals had aboveaverage intelligence. Hermann Göring had an IQ of 138.
25. Dolph Lundgren: A Hollywood Genius
Actor Dolph Lundgren, famous for playing Ivan Drago in Rocky IV, has an IQ of 160 and studied chemical engineering at MIT.
26. Firstborn Children Tend to Have Higher IQs
Studies suggest that firstborn children often have slightly higher IQs than their younger siblings due to early parental attention and responsibilities.
27. IQ and Obesity
Research has found a correlation between lower childhood IQ and higher rates of obesity in adulthood.
28. Chess and IQ: No Strong Link
Despite common belief, there is no significant correlation between a chess player’s IQ and their rating. Korean Go champions, for example, have an average IQ of 93.
29. The Genius with No Brain
Neurologist John Lorber discovered a university student with a neargenius IQ despite having almost no brain tissue due to hydrocephalus.
30. The Smartest Living Person?
As of 2024, Young Hoon Kim holds the world’s highest recorded IQ at 276.
31. Religion and IQ
Studies suggest a negative correlation between IQ and religious belief, though this remains a debated topic.
32. Emotional Intelligence (EQ) vs. IQ
Emotional intelligence (EQ) is a stronger predictor of career success than IQ.
33. Board Games Can Increase IQ
Studies show that playing logic based board games can raise children’s IQ by up to 10 points.
34. The Harvard Happiness Study
A Harvard study found that strong personal relationships are better predictors of happiness and longevity than IQ.
35. The Most Exclusive HighIQ Society
The Mega Society only admits people with IQs in the 99.9999th percentile. It has only 26 members.
36. Hong Kong’s High IQ
Hong Kong has the highest average IQ (107), followed by South Korea and Japan.
IQ remains a fascinating and complex topic. While intelligence plays a role in success, happiness, and health, it is far from the only factor that defines a person’s potential.
37. IQ and the Decline of “Genius” as a Classification
By 1937, psychologists stopped using the term “genius” as an official IQ classification. David Wechsler, creator of the Wechsler Intelligence Scale, argued in 1939 that it was inappropriate to define genius based on a single test score.
38. Marilyn vos Savant’s Record breaking IQ
Marilyn vos Savant was once listed in the Guinness Book of World Records for having the highest recorded IQ (228). However, her score was based on an outdated testing method, leading to Guinness eventually discontinuing IQ record tracking.
39. The Stress of Poverty Can Lower IQ
Financial stress can reduce cognitive function by an average of 14 IQ points. The constant pressure of financial insecurity affects problem solving and decision making abilities.
40. The Tragic Story of Brandenn Bremmer
Brandenn Bremmer had an IQ of 178, read books at 18 months, played piano at 3, and started college at 11. Despite showing no signs of depression, he tragically committed suicide at age 14.
41. Sharon Stone’s Mensa Controversy
For years, actress Sharon Stone claimed to have an IQ of 148 and to be a member of Mensa. However, in 2002, she admitted she had never actually been part of the highIQ society.
42. Isaac Asimov’s Reluctance Toward Mensa
Science fiction writer Isaac Asimov, despite being a Mensa member and vice president, disliked the organization’s elitist attitude. He criticized some members for being overly proud of their intelligence.
43. A High IQ Reduces Schizophrenia Risk
Research suggests that individuals with higher IQs are less likely to develop schizophrenia. Intelligence may provide cognitive resilience against some psychiatric disorders.
44. Americans Tend to Overestimate Their Intelligence
A 2009 survey found that 65% of Americans with only a high school education believed they had aboveaverage intelligence—despite data showing only 47% did. Among college graduates, 73% believed they were above average, but the data actually supported 84% of them.
45. Drinking Too Much Water Can Kill Even a Genius
A woman with an IQ of 189 died after drinking 4 gallons of water in one sitting while trying to treat her stomach cancer. Excessive water intake can lead to fatal water intoxication.
46. The Power of Board Games for Children’s IQ
Playing board games that involve logic and strategy, such as Qwirkle, can boost children’s IQ scores by up to 10 points in just eight weeks.
47. The Harvard Study on Happiness and Intelligence
A Harvard study (1938–2017) found that happiness and strong relationships are more important for long term health than IQ, wealth, or genetics. People in happy marriages had slower cognitive decline than those in stressful relationships.
48. The Most Exclusive HighIQ Society: The Mega Society
The Mega Society is one of the most exclusive highIQ groups in the world, requiring an IQ in the 99.9999th percentile (approximately one in a million). It has only 26 members.
49. The Surprising Case of a Genius Without a Brain
Neurologist John Lorber discovered a man with an IQ of 126 who had almost no brain tissue due to hydrocephalus. This raised questions about how intelligence is stored and processed in the brain.
50. January Schofield: A Genius with Childhood Schizophrenia
January Schofield had an IQ of 146 at age 4 and knew the alphabet at 13 months old. However, she also experienced violent hallucinations and was diagnosed with childonset schizophrenia, one of the rarest mental health conditions.
Final Thoughts
IQ is an intriguing but complex measure of intelligence. While a high IQ can provide advantages, it does not guarantee success, happiness, or good decision making. Emotional intelligence, perseverance, and social skills play equally—if not more—important roles in shaping a person’s life. Intelligence is not fixed, and factors such as education, environment, and even nutrition can influence cognitive abilities over time.
