Biological Approach - Genetics and Behaviour - Genetic Similarities

Question 1

Gene

Answer 1

• The biological unit of heredity
• Humans have 46 hromosomes, made up of 23 from the father, and 23 from the mother
• Each chromosome is composed of many individual heredity units called genes
  
  • a gene is a segment of DNA
• They are thought to be responsible for the development of physical and behavioural characteristics

Question 2

Monozygotic Twins (MZ)

Answer 2

• Genetically identical because they are formed from one fertilised egg that splits into two
• Same sex
• Very similar look

Question 3

Dizygotic Twins (DZ)

Answer 3

• No closer genetically than brother or sisters
  
  • 50% genes in common
• Formed from 2 seperated fertilised eggs
• Not necessarily the same sex

Question 4

Genetic Similariy Hypothesis

Answer 4

The higher the genetic relationship, the more similar individuals will be if the particular characteristics being investigated is inherited.

Question 5

Concordance Rate

Answer 5

• How similar two individuals are
• 0= not similar at all
  1= completely identical

Question 6

Falconer’s Heritability

Answer 6

• Assumes that phenotype is comprised of 3 types of influence
  
  • Genetics (A)
  • Shared environment (C)
  • Individual Environment (E)
• 1 = A + C + E

Question 7

Rushton et al. (1986)

Answer 7

Aim:
- Examine genetic influence on individual differences in altruism and aggression

Pps:

• 573 adult twin pairs of both sexes
  
  • Identical and fraternal twins raised together

Procedure:

• 5 questionnaires measuring: altruism, empathy, nurturance, aggressiveness and assertiveness
• Correlations calculated for each trait

Results:

• Correlations were .53, .54, .49, .40, .52 for MZ
• Correlations were .23, .20, .14, .04, .20 for same sex DZ
• Heritability estimates: 56%, 68%, 70%, 72% and 64%
• Women had higher scores than men on altruism and lower scores on aggressiveness
• Altruism increased over the age span of 19-60 and aggressiveness decreased