IB Psychology HL - BLOA - To What Extent Does Genetic Inheritance Influence Behaviour?

• behaviour causing pain/harm in others

• labeled as aggression only when the behaviour is intended to cause harm

a doctor giving an injection causes pain but the act isn’t aggressive as his intention isn’t to harm the individual

• animal studies have shown clear link between aggression and genetic inheritance

Cited studies:

• Bock and Goode (1996)

• Suomi and Lesch (2002)

investigate effects of serotonin on aggression

2 conditions:

• serotonin inhibited

• control

• low serotonin levels are correlated with aggression

• mice in the first condition had their serotonin receptor sites genetically manipulated via breeding

• by having the gene responsible for producing serotonin receptor proteins removed

• aggression was measured by the amount of bites/attacks

serotonin-inhibited mice reared without aggressive role models still showed aggressive behaviour

aggression can be correlated with genetics

• tightly controlled

• quantifiable and clear IV/DV

• ethical guidelines for treatment of animals followed

• as animals were bred for experimental purposes

• identified a gene that affects effectiveness of processing serotonin

• cerebral spinal fluid of 132 juvenile rhesus monkeys was collected

• analysed for serotonin metabolite traces (high metabolite level = high efficiency of serotonin processing)

• monkeys that had low metabolite levels were more aggressive

• animal studies have shown clear link between aggression and genetic inheritance

• but it’s reductionist and simplistic to assume genes are solely responsible for complex behaviour

• aggression is a complex human behaviour

• unlikely to be the result of one genetic trait

• more likely the result of a combination of environmental and genetic factors

• factors in the environment (e.g. parenting) must always be considered

cited studies:

• Suomi (2002)

• Caspie and Moffitt (2012)

• noted that bullies came from stern mothers while neurotics came from shy mothers

• he took neurotic babies (babies that had nervous dispositions) from neurotic mothers

• gave them to nurturing mothers (supermoms)

• when raised by supermoms, the babies turned out very close to normal

• shows that environment has a clear impact on behaviour

• conducted 26 year longitudinal study

• involved 1036 children born in 1972 NZ

• children inheriting a short version of the gene MAOA were more likely to exhibit aggression

• but this was only in cases where the children experienced an abusive upbringing

• carriers of MAOA who experienced good parenting were usually normal

Strengths:
- helps us determine the effect of particular genes on behaviour

Weaknesses:

• genes interact with the environment in complex ways

• knowledge about genes is still limited

Strengths:

• animal studies allow high levels of manipulation that would not be allowed on humans

• findings help us understand biological mechanisms

Weaknesses:
- caution should be used when generalizing findings
of animal studies to humans

• define aggression

• describe + explain the link between genes and aggression – Bock and Goode (1996), Suomi and Lesch (2002)

• investigate alternate factor (effect of environment on behaviour) – Suomi (2002), Caspie and Moffitt (2012)

• evaluate studies mentioned

• discuss the ecological validity of genetic research

• weigh benefits and limitations of using genetic research to understand behaviour

• when stating opinions, mention empirical evidence

• form a clear conclusion by discussing the relative importance of genes vs environment on behaviour