Genetics vs. Environment

Intelligence

• Piaget (1954) intelligence is innate at birth but develops at different stages through biological maturation (different things become available at different ages)

• Largely genetic component

• Flynn effect – IQ has overall gone up by 20 points in the last 30 years, showing a clear environmental impact

• Turkheimer et al (2003) 60% of variance in affluent families is due to genes, however, in poorer families, it could account for no variance, showing clear environmental impact

Mental Illness

• Joseph (2004) 40.6% concordance for schizophrenia in MZ twins

• Tienari et al – adopted children with schizophrenic mothers are still more likely to have schizophrenia

• Must be some environmental influence or we would expect 100% concordance

Evolutionary

• Natural selection theory, traits which benefit our survival are passed on

• Fight or Flight response

• Selye (1936)

• Buss – mating choice is universal, modified by culture

Influences

• Active influence – children seek out experiences to suit their genes, e.g. a predisposed genetically aggressive child will seek to be aggressive

• Passive influence – parents genes effect the environment they create for their children e.g. schizophrenic parents are emotionally flat towards their children causing them to become schizophrenic

• Reactive influence – genes directly change the environment

Phenylketonia

• Inherited genetic disorder affecting amino acids

• Controlled by diet

Politics

• Selective human breeding if nature is correct - Hitler

• Engineering correct behaviour is environment is correct – Pol Pot

• Massive ethical issues in deciding upon which is correct

Nurture

• Due to behavioural learning, interaction and experience

Aggression

• SLT – Bandura (1961)

• This theory doesn’t ignore biology, it recognises that a potential for aggression is genetic whilst expression of aggression is learnt

Neural Plasticity

• Maguire et al (2000) London Taxi drivers have enlarged hippocampi, showing how their brains have developed for more spatial awareness and planning

• Edwards and Cline (1999) neurones shrink and grow in response to environmental change

• Blakemore and Cooper – Kitten study

Environmental Inheritance

• Epigenetics – genes are turned on and off due to our environment

  • Why clones don’t produce exact copies