Hereditary Influences

Question 1

Describe four different ways of gene expression

DoCoGePo

Answer 1

1. Dominant-Recessive
   - One relatively powerful allele dominates other allele so that only its phenotype is expressed
2. Co-Dominance
   - Phenotype is a compromise between two genes
3. Genetic imprinting
   - Particular genes are bio-chemically marked so that only one parent’s allele is expressed
4. Polygenic inheritance
   - Multiple pairs of alleles contribute to phenotype

Question 2

Describe how heritability of a psychological attribute is estimated

meaning + 2 points

Answer 2

Correlations between pairs of individuals reflect degree of similarity
1. Identical twins vs. fraternal twins
2. Siblings vs. adoptive siblings

Question 3

Explain the difference between “shared” and “non- shared environment”

Answer 3

Shared: Common to all children who grow up in the same family
- Shared environment accounts for psychological similarity

Non-shared: unique to each child within the same family
- E.g. birth order, friends, interests, IQ

Question 4

Outline common misconceptions of heritability estimates and explain why they are misconceptions

Answer 4

1. Heritability does not mean “inherited
2. Heritability estimates are not “natural” constants
3. Heritability estimates do not imply genetic determinism
4. Heritability estimates are about variability in populations NOT
   individuals

Question 5

Describe two different ways how genes and environment interact

2 Principles

Answer 5

1. Canalization Principle: Genes limit or restrict development to a small number of outcomes
   - Effects of environment depend on genetic factors
   - ex; Imprinting: innate form of learning in which young ducklings become attached to moving objects
2. Range-of-Reaction Principle: Genotypes establish a range of possible outcomes
   - Range differs across individuals
   - Genes define range of reaction (= possible outcomes)
   - ex; Body size is influenced by genes and environment (e.g. nutrition)

Question 6

Describe three different ways how genes and environment are
correlated

APE

Answer 6

1. Active
   - active becomes more important with age
   - Children prefer and seek out environments that are most compatible with their genetic predispositions
2. passive
   - Passive becomes less important with age
   - Home environment provided by parents is in part influenced by parent’s genotype
   - ex; Parents who are musical create musical home for their children, at the same time children inherited musical genes
3. evocative
   - A child’s genetically influenced attributes affects behavior of others towards him or her