Genetic Inheritance

Question 1

What are twin studies?

Answer 1

Used to study human behaviour in order to estimate the heritability of a given trait or behaviour

Question 2

How are twins studied?

Answer 2

• Studied twins raised in shared and non-shared family environments
• Includes MZ twins (share 100% DNA) and DZ twins (share 50% DNA)

Question 3

How is behaviour measured?

Answer 3

• Tests and diagnoses

* After data collection similarities and differences of MZ and DZ twins are calculated by concordance rate

Question 4

What is concordance rate?

Answer 4

Measure of how similar an average for a behaviour twins are

Question 5

Behaviour and concordance

Answer 5

• Measures the probability that if one twin has a particular characterstic, the other twin will also have it

Question 6

What are kinship studies?

Answer 6

Used to assess how degrees of genetic relatedness are compared to specific behaviours

Question 7

Reasons and causes for kinship studies

Answer 7

• Based on understanding that a child inherits half their genes from each parent
• First degree relatives (siblings) will share 50% of their DNA, second degree relatives (grandparents) 25% and third degree relatives (first cousins) 12.5%

Question 8

What is heritability?

Answer 8

The proportion of phenotypic variance attributable to genetic variance

Question 9

Diathesis stress theory

Answer 9

• Theory that predicts individual’s reactions to stressful life events based on genes
• E.g. depression
• Those with the short-short 5-HTT (serotonin transporter gene) allele are more likey to develop depression when faced with a stressful life event, those with the short-long are less likely and those with the long-long allele are least likely

Question 10

What is a gene?

Answer 10

Genes are hereditary units of behaviour which encode for specific traits. They are basic units of life and encode for specific proteins which then can influence behaviour

Question 11

Genetic inheritance strengths

Answer 11

Genetic similarities:
- These types of studies give some idea of whether a behaviour is inherited
- Twin studies compare MZ and DZ with other siblings
- Adoption studies address environmental factors

Question 12

Genetic inheritance limitations

Answer 12

One gene in behaviour:
- No behaviour results from a single gene
- Genetics is a reductionist approach to behaviour
- Many studies had issues with construct validity

Genetic similarities:
- May be retrospective studies which rely on childhood memories and may be unreliable
- Studies do not tell us which genes may be responsible