2g. Genes and behaviour Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Nature vs Nurture debate

A

Establishes whether human behaviour is determined primarily by biological factors or environmental

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Diathesis-stress model

A

Predicts that an individual with certain genes, when exposed to a stressful environment, is more likely to develop depression than someone who doesn’t have those genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What argument does diathesis-stress model support?

A

Argument that a person may have a genetic predisposition towards a behavior, however without appropriate environmental stimuli, gene is not “activated” and hence will not be expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Indirect methods of genetic research

A
  1. Kinship/family studies
  2. Twin studies
  3. Adoption studies
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Direct methods of genetic research

A
  1. Linkage studies

2. Genome wide association studies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Monozygotic twins

A

Those who develop from same egg and share 100% genotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Dizygotic twins

A

Develop from different eggs and share 50% genotype, like regular siblings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Concordance rate

A

Probability that same trait will be present and expressed in both twins. Rarely ever 100%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Principle of genetic relatedness

A

The higher the genetic similarity between two individuals, the more likely it is for a particular characteristic to be present in both individuals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are twin studies used?

A
  • Identical twins allow us to study effect of genetics

- Fraternal allow us to see the effect of environment as they have different DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Limitations of twin studies

A
  • Twins are rarely raised apart so they experience similar environment hence difficult to isolate environmental influence as a variable
  • Equal environment fallacy
  • Twins are not highly representative of general population- less generalizability
  • Concordance rate is rarely 100% so genetics can never be implied as direct causation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Equal environment fallacy

A

Assuming that twins grow in equal environment. We have to be careful not to overestimate the similarity of environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Family studies

A

Look at concordance rate within a family, usually over 3 generations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why are family studies used?

A
  • Sample is more representative of general population

- Allows for similarity in culture and environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Limitations of family studies

A
  • Members share same environment
  • No actual gene identification
  • Anecdotal/ self-reported data
  • Waiting for generations is an inefficient strategy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Adoption study

A

Comparing adopted children to their biological and adopted parents and biological/adopted siblings to determine higher concordance rates

17
Q

Why use adoption studies?

A
  • Easier to infer exact influence of genetics
  • Allow researcher to more directly investigate role of environment and genetics
  • Research can isolate variables
18
Q

Limitations of adoption studies

A
  • Children are not representative of the general population

- Adoption tend to use selective placement when finding homes

19
Q

Which twin study can be used for depression?

A

Kendler et al. (2006)

20
Q

Kendler: Aim

A

To investigate the role of genetics in depression

21
Q

Kendler: Procedure

A
  • Carried out twin study of over 20000 twin pairs in Swedish national twin registry
  • Studied monozygotic and dizygotic twins
  • Researchers used a team of interviewers to carry out telephone interviews
  • They assessed lifetime major depression by using modified DSM-IV criteria
  • Questions were also asked regarding the environment they lived in
22
Q

Kendler: Results

A
  • Over 8000 twins met criteria for depression while around 300 discussed discussed history of anti-depressant treatment
  • Found avg. CR for MZ male twins was 31% while for MZ female twins was 44%
  • 11% and 16% for DZ male and female twins
  • Genetic risk factors may be sex-specific
  • No correlation between no. of years in shared environment and depression
  • CR is way below 100% so genetics is not cause but rather a vulnerability
23
Q

Kendler: Evaluation

A
  • Studies are correlational
  • No specific genes identified
  • Other twin studies have had similar results so its reliable
  • All data was self-reported
  • Investigators relied on previously accepted diagnoses
  • Sample size was large
24
Q

Family study for depression

A

Weissman et al. (2005)

25
Q

Weissman: Aim

A

Study the potential genetic nature of MDD

26
Q

Weissman: Procedure

A
  • Took place over 20 year period
  • Sample of 160 grandchildren and their families
  • Original sample of depressed patients (grandparents) was selected from specialized clinic. Non-depressed patients were also selected
  • All 3 generations were interviewed many times and data was collected by clinicians blind to past diagnosis of depression
  • Researcher triangulation was used to establish credibility of diagnosis. Used psychiatrist and psychologist
27
Q

Weissman: Results

A
  • High rates of psychiatric disorder in grandchildren with two generations of depression
  • Less risk if it wasn’t observed in second generation
  • Severity of parent’s depression was correlated with increased rate of mood disorder in children
  • If parent was depressed but no history in grandparent, no significant effect on grandchild
28
Q

Weissman: Evaluation

A
  • Study is longitudinal so reliable
  • Association between parent and child is moderated by grandparent
  • Use of research triangulation
  • Sample is large but not many replications
  • No genotype is studies but it indicates potential genetic link
  • 3 generations is limited however to go further back, one is reliant on memory and anecdotal data= distortions