2g. Genes and behaviour Flashcards
Nature vs Nurture debate
Establishes whether human behaviour is determined primarily by biological factors or environmental
Diathesis-stress model
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
What argument does diathesis-stress model support?
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
Indirect methods of genetic research
- Kinship/family studies
- Twin studies
- Adoption studies
Direct methods of genetic research
- Linkage studies
2. Genome wide association studies
Monozygotic twins
Those who develop from same egg and share 100% genotype
Dizygotic twins
Develop from different eggs and share 50% genotype, like regular siblings
Concordance rate
Probability that same trait will be present and expressed in both twins. Rarely ever 100%
Principle of genetic relatedness
The higher the genetic similarity between two individuals, the more likely it is for a particular characteristic to be present in both individuals
Why are twin studies used?
- Identical twins allow us to study effect of genetics
- Fraternal allow us to see the effect of environment as they have different DNA
Limitations of twin studies
- 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
Equal environment fallacy
Assuming that twins grow in equal environment. We have to be careful not to overestimate the similarity of environment
Family studies
Look at concordance rate within a family, usually over 3 generations
Why are family studies used?
- Sample is more representative of general population
- Allows for similarity in culture and environment
Limitations of family studies
- Members share same environment
- No actual gene identification
- Anecdotal/ self-reported data
- Waiting for generations is an inefficient strategy