Question
Is IQ genetic?
Short answer
Partly. Research estimates the heritability of intelligence at about 20% in infancy, rising to perhaps 80% in later adulthood. Heritability describes how much of the variation between people in a group links to genetic differences. It does not mean 60% of any one person’s IQ comes from their genes.
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What the research found
A widely cited review by Plomin and Deary reports that the heritability of intelligence rises with age, from roughly 20% in infancy to perhaps 80% in later adulthood (Plomin & Deary, 2015). In plain terms, as people grow up, more of the differences between them in measured intelligence line up with differences in their genes.
Try one · Logical Reasoning
Which tile completes the second pair?
Tap the option you think is right, or show the answer.
Show the answer
The missing panel shows a small solid square, with small solid shapes: a triangle at the top-left corner and a triangle at the bottom-right corner (option 6).
How to solve it
- Compare the first two panels and name exactly what changed.
- The main shape and the small shapes swap forms: the main shape takes the form of the small ones, and the small ones take the form of the main shape.
- Nothing else changes.
- Apply the same change to the third panel: a small solid triangle pointing up, with small solid shapes: a square at the top-left corner and a square at the bottom-right corner.
- So the missing panel shows a small solid square, with small solid shapes: a triangle at the top-left corner and a triangle at the bottom-right corner.
That was 1 puzzle. The full test has 25.
What heritability is, and is not
Heritability is a statistic about a group of people in a particular setting. It answers: of all the variation in scores in this group, how much tracks genetic variation? It does not say what share of your own score came from genes, and it can differ between populations and environments.
It also does not mean a trait is fixed. Average measured IQ rose through the 20th century, by about 2.8 points per decade in a 2015 meta-analysis of 271 samples (Pietschnig & Voracek, 2015). Gene pools do not change that fast, so this rise points to environmental change across generations. A trait can be highly heritable within a group and still move on average over time.
What it means for you
Not much, on its own. A heritability estimate cannot predict your score or tell you how far it could change. Your measured IQ also moves for ordinary reasons: practice, measurement error and the test you take. See can your IQ change for those.
If you want the definitions, the glossary covers heritability and general intelligence. For what an IQ test actually measures, read the guide what does an IQ test measure.
Sources
- Plomin, R., & Deary, I. J. (2015). Molecular Psychiatry, 20, 98-108. doi.org/10.1038/mp.2014.105
- Pietschnig, J., & Voracek, M. (2015). One century of global IQ gains. Perspectives on Psychological Science, 10(3), 282-306. doi.org/10.1177/1745691615577701