Intelligence Research

How much of your IQ actually comes from your parents? Explore twin studies, heritability data, and the surprising ways genetics and environment shape intelligence across generations.

Your grandparents would score about 15-20 IQ points lower on today's tests -- not because they were less capable, but because of the Flynn effect. Here is a simple explanation of why IQ scores rise over time, what drives the gains, and why they may be reversing.

What makes some people score higher on IQ tests? This pillar guide covers the g-factor, CHC theory, brain imaging research, and the genetics-environment debate -- everything science knows about human intelligence in one place.

What does IQ actually measure? This comprehensive guide covers the g-factor, CHC theory, how major IQ tests like the WAIS-IV and Stanford-Binet 5 calculate scores, what different IQ ranges mean, and how to interpret your results.

How did Alfred Binet's 1905 intelligence test in Paris lay the groundwork for modern IQ assessment? Explore the French education crisis that sparked the invention, the Binet-Simon Scale's design, and how intelligence testing evolved over 120 years.

How do average IQ scores compare across age groups and countries? Explore cross-national IQ data, age-based cognitive norms, and the environmental and genetic factors that shape intelligence worldwide.

How much of IQ is genetic? Twin studies estimate 40-80% heritability. Explore GWAS findings, gene-environment interaction, epigenetics, and what heritability really means for your intelligence.

Review the strongest evidence for educational interventions that raise IQ: Head Start, Perry Preschool, the Abecedarian Project, music training, and bilingual education -- with effect sizes, fadeout evidence, and long-term outcomes.

Compare national IQ averages across 50+ countries with 2025 data tables, examine how the Flynn Effect varies by region, and understand why researchers urge extreme caution when interpreting cross-national IQ comparisons.

From the Bell Curve debate to race-IQ disputes and test bias allegations, explore why intelligence research remains one of science's most contested fields -- and what the evidence actually shows.

From Alfred Binet's 1905 scale for French schoolchildren to AI-powered adaptive testing, trace 120 years of IQ test history through the key milestones, controversies, and breakthroughs that shaped how we measure human intelligence.

What does 100+ years of IQ research actually say about sex differences in intelligence? We examine the greater male variability hypothesis, domain-specific cognitive gaps, and stereotype threat -- separating scientific evidence from persistent myths.