I&D 03/04: Nature- nurture (b) A03

Explain what results from twin studies have shown about the role of genes and environment in schizophrenia (5)

* MZs concordance = 48%

* DZs concordance = 17%

* MZs much more similar => moderate / large genetic effect

* But, concordance nowhere near 100%, so likely to involve environment somehow

* Studies such as Tienari's have found direct evidence for interaction between genes and environment

Explain how the diathesis-stress model accounts for schizophrenia (3)

* Interactionist explanation

* It results from a genetic vulnerability, i.e., diathesis...

* ... triggered by stress e.g. dysfunctional family relationships.

Explain the key limitation of twin studies (3)

* MZs may be treated more similarly than DZs.

* Their higher concordance may be due in part to them being raised in a more similar environment...

* ... rather than sharing all of their genes.

Explain why adoption studies are considered a better method than twin studies for testing the influence of genes and environment (4)

* Adoption studies separate genetic and environmental influence

* Children have genetic (nature) and adoptive (nurture) parents

* Similarity to genetic parents suggests influence of nature

* Similarity to adoptive parents (or adoptive siblings) suggests influence of nurture

Explain why studies that show an association between environmental factors and psychological outcomes are only weak evidence for the role of the environment.

Illustrate your answer with reference to studies of parental behaviour and adult attachments.

* Outcome could be due to genes, not environment

* Parent provides genes and environment

* Adult attachments could be secure because of sensitive parenting (environment / nurture)...

* ...or because someone who parents sensitively also has genes which lead to secure relationships (nature)

Explain what is meant by epigenetics. (4)

* A change in genetic activity without a change to the genotype.

* The environment leaves epigenetic ‘marks’ (‘tags’) which turn genes on or off.

* Some marks survive in egg and sperm cells...

* ... meaning that a person’s experience can affect the lives of future generations.

Explain what is meant by the term heritability co-efficient (3)

* Numerical value (between 0 and 1)

* Expressing the degree / extent of genetic influence

* Proportion of differences between individuals in a population (e.g., in intelligence) that is due to genetic variation.

* Measure of strength of nature

Explain negative political associations of extreme nature and nurture viewpoints (2+2)

Nature

* Attempted to link ethnicity, genetics and intelligence

* Application of eugenics policies

Nurture

* May lead to a model of society that controls and manipulates its citizens using behavioural techniques

* Which is pretty much what Skinner wanted

Explain the importance of the concept of interaction in the nature nurture debate (2)

* No behaviour is due entirely to nature or nurture

* Everything is due to interaction between biology and environment