Genes and behaviours

Question 1

Define genes

Answer 1

A unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Question 2

The “nature-nurture” debate

Answer 2

Attempts to establish whether human behaviour is determined primarily by biological factors (genetics) or environmental factors (education, friends).

Question 3

Genetic similarities

Answer 3

Genetic similarity is referred to as relatedness. The greater the genetic similarities between two individuals or a group of individuals the higher the degree of relatedness.

Question 4

Twin study

Answer 4

Bouchard et al (1981)

Question 5

Aim

Answer 5

to investigate the effect of genetic inheritance in intelligence.

Question 6

Procedure

Answer 6

• Twin study

- Conduct a meta-analysis of 111 studies on IQ correlations between relatives

Question 7

Results

Answer 7

• MZ twins raised together has higher median correlation of 85 % than 67% of MZ twins raised apart
• MZ twins raised together has higher median correlation of 85% than 58 % DZ twins raised together
• When twins and family members are raised in the same environment, the degree of similarity in IQ is higher when the genetic heredity is closer
• When identical twins are raised in different environment, similar environment would result in higher probability of intelligence inheritance
• Both genetic and environmental factors play a role in genetic inheritance in intelligence.

Question 8

Evaluation

Answer 8

• small sample size, fewer opportunities for replication
• twins are not representatives of the general population
• no control for the effect of environmental variables
• calculation of concordance rates is not reliable

Question 9

Gene-environment

Answer 9

Caspi et al (2003)

Question 10

Aim

Answer 10

To determine whether there is evidence for a gene-environment interaction for a mutation of the serotonin transporter gene-5-HTT

Question 11

Procedure

Answer 11

• 5-HTT gene influences level of serotonin (control mood)

- Compare participants with a normal 5-HTT gene and a mutation of the 5-HTT gene with shorter alleles

Question 12

Results

Answer 12

• Participants who carried a mutation of 5-HTT gene have 80% to become depressed than normal 5-HTT gene after stressful events
• Adult depression due to childhood mal-treatment only discovered in those with short alleles
• The 5-HTT gene indicate a vulnerability to depression after stress which suggests that gene could moderate individual responses to environmental factors

Question 13

Evaluation

Answer 13

• Correlational (no cause-and-effect relationship)
• It’s an assumption
• Environmental factors should also be considered
• Holistic approach(not reductionist), environmental factors could also be considered