Glossary
Heritability
Definition
Heritability is the share of the differences between people in a trait, within a particular population and time, that is linked to genetic differences between them. It is a statement about variation in a group, not about how much of one person's trait comes from their genes.
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What the research found
Heritability of intelligence rises with age, from about 20% in infancy to perhaps 80% in later adulthood (Plomin & Deary, 2015). That rise is itself a clue that heritability is not a fixed constant: it depends on the population and the stage of life being studied.
An example
Height is highly heritable in well-fed populations, yet average height rose across generations as nutrition improved. High heritability within a group does not mean a trait cannot change, and it does not tell you why two groups differ. The same logic applies to IQ, where average measured scores rose for decades (see the Flynn effect).
Common confusions
- Heritable does not mean fixed or unchangeable.
- Heritability is not the same as “inherited from your parents” in a simple sense.
- It says nothing about differences between groups, only variation within the group studied.
For a direct answer, read is IQ genetic? Related terms: correlation, general intelligence and age norms. For the bigger picture, see what an IQ test measures.
Why it rises with age
In about 11,000 twin pairs, the heritability of general cognitive ability rose from 41% at age 9 to 55% at 12 and 66% at 17 (Haworth et al., 2010). The researchers suggest gene-environment correlation: as children grow up, they increasingly select, modify and create their own experiences, partly in line with their genetic propensities (Haworth et al., 2010). More in genes and intelligence.
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 hatched circle, with small solid shapes: a triangle at the bottom (option 2).
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 hatched triangle pointing up, with small solid shapes: a circle at the bottom.
- So the missing panel shows a small hatched circle, with small solid shapes: a triangle at the bottom.
That was 1 puzzle. The full test has 25.
Sources
- Plomin, R., & Deary, I. J. (2015). Molecular Psychiatry, 20, 98-108. doi.org/10.1038/mp.2014.105
- Haworth, C. M. A., et al. (2010). The heritability of general cognitive ability increases linearly from childhood to young adulthood. Molecular Psychiatry, 15(11), 1112-1120. doi.org/10.1038/mp.2009.55