PSYCH Lecture Week 14
Genetics and Intelligence
The basic unit of heredity is called a: gene.
The question used to be: Is nature or nurture responsible for development?
Now the question is: How do nature and nurture interact to affect development?
Nature: genes we receive from our parents.
Nurture: all of the physical and social environment.
Genotype: The nucleus of every cell contains 23 pairs of chromosomes.
• Genes are sections of the chromosomes
• Each gene is a segment of the DNA that codes for a production of one particular
• 22 of these pairs are roughly equal and carry the same gene sequences relevant to
Genotypes and Phenotypes
Genotype – the complete set of genes that you inherit from your parents
Phenotype – the observable expression of your genotype including both appearance and
behaviour. Phenotype affected by environment even before conception.
Most human genetics depend on a single gene: false! Most genetics depend on many
The degree to which the variability of a particular trait in a particular population is a
result of genetic differences among those organisms.
• Not individuals but groups.
• Intelligence studied a great deal: heritability estimate of 50%.
• Remember that genes only code for proteins.
• Only applies to a particular group living in a particular environment at a particular
point in time.
• Tease apart environmental and genetic contributions
• Family, twin and adoption studies
• Ideal behavioural genetics study combines twin and adoption.
On average, behaviouralgenetics studies estimate the heritability of intelligence to be:
higher for adults than children.
Intelligence • An individual’s ability to understand complex ideas, to adapt effectively to he
environment, to learn from experience, to engage in various forms of reasoning,
and to overcome obstacles through mental effort.
• What and how is controversial.
Is intelligence one thing or many
Fluid vs. Crystallized intelligence
Fluid intelligence decreases with age. Fluid intelligence has to do with acquiring new
ways to overcome obstacles. Alter your behaviour thanks to new knowledge.
Crystallized intelligence is knowledge. The acquiring of information.
Gardnertheory of multiple intelligences
Popular in the field of education – littl