A - Genetic Factors Flashcards
How can chromosomal activity cause aggression?
Males with an extra Y chromosome are thought to be predisposed to be violent criminals - XYY
Tend to be above average height, below average intelligence - these males are over represented in prisons
How can genetic factors cause aggression?
Aggression runs in families - could be genetic
Research into behavioural genetics has shown that most aspects of behaviour are influenced by heredity in some degrees
What is the MAOA gene/how can it cause aggression?
Warrior gene
Affects our ability to regulate aggression
Under normal circumstances, it controls the production of the MAOA enzyme which in turn controls serotonin and dopamine levels
A mutation of the MAOA gene means that abnormal levels of the enzyme are produced and hence aggression is not properly regulated
What did Jacobs find that supports the chromosomal explanation?
Found that there were 15:1000 individuals in prison with the XYY chromosome, compared to 1:1000 in the normal population
What is a criticism of Jacobs study?
Most individuals with the XYY chromosome were in prison for property related crimes - not very aggressive so may not be the cause
How does Theilgaards research go against Jacobs’?
Showed XYY men tend to seem more aggressive but these tendencies didn’t mean that they could perform aggressive acts and go to prison
What did McGuffin and Gottesman find that supports the genetic explanation?
Found a concordance rate of 87% in MZ twins for aggressive and anti-social behaviour and 72
5 in DZ twins - aggression could be inherited as they share parents/genes
How do Hutchins and Mednick supports McGuffin and Gottesman?
Found a positive correlation between the number of convictions for criminal violence among the biological parents and the number of convictions for criminal violence among their adopted sons - rules out nurture factors
What did Brunner find that supports the MAOA explanation?
Found a marker on the Y chromosome which was present in all violent men in a Dutch family, but never in the non-violent men
What is wrong with Brunners study?
Unique case study - cannot be generalised to all families as it may not be the case for everyone and there may be other genetic factors present
