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Biological perspective II. How do evolution and heredity influence behaviour? Old nature:nurture debate not very meaningful How has heredity limited/enhanced potential? How has environment limited/enhanced potential?. Heredity and behaviour. The GENOTYPE - genes involved in particular trait
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Biological perspective II • How do evolution and heredity influence behaviour? • Old nature:nurture debate not very meaningful • How has heredity limited/enhanced potential? • How has environment limited/enhanced potential?
Heredity and behaviour • The GENOTYPE - genes involved in particular trait • The PHENOTYPE - the trait itself as manifested in the individual • Genotype fixed, phenotype develops • Organism a product of interaction between genes and environment
Behavioural genetics • Research field investigating relative effects of heredity and environment on behaviour and ability • Heritability -proportion of trait variance attributable to genetic variation • Methods include twin studies and adoption studies
Behavioural genetics • Twin method: examine identical (monozygotic) and fraternal (dizygotic) twins for resembling characteristics • Adoption method: examine children adopted soon after birth - compare characteristics/abilities to biological and adoptive parents
Example - intelligence • Ability to learn from experience • Adapt to environment • Solve problems through mental activity • Engage in reasoning
Old studies- IQ • Burt 1953, Shields 1964 - identical twins raised apart seen to have highly correlated IQs (but flaws revealed in Burt study) • Skodak & Skeels 1949 - IQ of adopted children matched to natural parents • Scarr & Weinberg 1976 - IQ of adopted children matched to adoptive parents
IQ and heritability • Genes do not necessarily determine IQ • A highly heritable trait can be highly modified by environment • Prenatal care, nutrition, finance, family circumstance, toxins • IQ scores in developed countries have risen over last eight decades
Heredity and behaviour • Genes do not fix behaviour, they establish a range of possibilities. Do they influence:- • Temperament? • Aggression? • Susceptibility to mental health problems?