1. 2.2 Biological level of analysis
Genetics and behaviour

3. Learning Outcomes First four are the same as in 2.1 New are:
Discuss the extent to which genetics influence behaviour
Examine one evolutionary explanation of behaviour
Discuss ethical considerations in research into genetic influences on behaviour

5. The developing child
This program traces the nature vs. nurture debate, revealing how developmental psychologists study the contributions of both heredity and environment to child development. With Dr. Renee Baillargeon of the University of Illinois and Dr. Judy De Loache of the University of Illinois

6. Is biology destiny?

7. Case Study 1. “A boy without a penis” handout
2. Money study on p. 37 same study
Read and comment
What is your response?

8. Behavioural genetics
Deals with understanding how both genetics and the environment contribute to individual variations in human behaviour
What is inherited may be one of the building blocks for such complex behaviours

9. Behavioural genetics
Psychologists argue that an individual may have a genetic predisposition towards a certain behaviour; however, without the appropriate environmental stimuli, this behaviour will not be manifested
An example of this is: the origin of depression

10. The diathesis-stress model
Is used to explain the origin of depression
This model argues that depression may be a result of the interaction of a “genetic vulnerability” and traumatic environmental stimuli in early childhood.
Not everyone who experiences a traumatic childhood or has someone in the family who becomes depressed, will be depressed, therefore there in no single cause-and-effect relationship between genes and behaviour

11. Genes
Humans have 24 distinct chromosomes, with app genes
Human genome project: mapping the genetic make-up of the human species by identifying those genes

12. Genetic research Is to a large extent based on correlational studies
What is that?

13. Twin studies, family studies and adoption studies
To study the possible correlation of genetic heritance and behaviour
But why?

14. Twin studies
There are two types of twins: monozygotic (MZ) and dizygotic (DZ)
Monozygotic twins: are genetically identical due to one fertilized egg that splits into two.
These twins are of
the same sex,
and look very much alike

15. Twin studies Dizygotic twins are from two eggs.
DZ twins are not any closer genetically than brothers and sisters, that is, they will have 50% of their genes in common.
They don’t have to be
of the same sex.

16. Twin studies
The hypothesis is that the higher the genetic relationship, the more similar the individuals should be if the particular behavior being studied is inherited.
The correlation found is called the concordance rate

18. Family studies A more representative sample of the general population.
A child inherits half of its genes from the father and half from the mother
Sibling will share 50% with each other
Grandparents will share 25% with their grandparents
First cousins will share 12,5% with each other

19. Family studies
These different degrees of genetic relatedness are compared with behaviour.
For example: if one study intelligence and believe that IQ has a lot to do with the genes, there should be a strong correlation in IQ between children and their mother and fathers, but a weak
correlation in IQ with
their second cousins
and if any with strangers

20. Adoption studies
Adopted or foster children generally share none of their genes with their adoptive parents, but 50% with their biological mother and father.

21. Adoption studies
Therefore, if the heritability of a behaviour is high, the environment should have little part to play
And the adopted children should correlate more strongly with the behaviour (e.g. IQ) of their biological mother and father than their adoptive parent.

22. Adoption studies Critique against using this method:
Not representative of the general population
Adoption agencies tend to use
selective placement when
finding homes
(as similar as possible)
Is Madonna a similar family?

23. To sum up
These methods help the researchers to determine the extent of genetic influence
There is a clear correlation between several behaviours and genetic heritance
We are going to examine Intelligence