XYY syndrome and link to aggression Flashcards
what is XYY syndrome
when a human male has an extra Y chromosome
prevalence rate
1/1000
random occurance at conception
percentage of males with XYY that go undetected
75%
examples of physical features of XYY syndrome
tall
cystic acne during adolescence
widely placed eyes
mental features of XYY
IQ is 10-15 points lower than siblings on average
increased risk for learning disabilities and behavioural problems (e.g. dyslexia, ADHD)
Jacobs et al. (1965)
3.5% of 196 males in a scottish state mental hospital in Edinburgh were XYY
why is Jacobs et al. good supporting research
studies of inmates in similar institutions in England, Austrailia, Denmark, USA found a similar percentage incidence
application of genetic testing
can be used to determine whether people have XYY
to see if they have a genetic predisposition to violence and aggression
preventative measures can be put in place - e.g. education on why violent crime isn’t acceptable or therapy to help reduce urges
Theilgaard et al. (1984) - opposing evidence
30000 men
12 of them had XYY and 16 had XXY
XYY males had slightly lower levels of intelligence than average and were found to be more aggressive toward other people
more similarities than differences found between XXY and XYY males - so no solid evidence of a criminal gene found
personality was administered by a social worker who did not know the aim of the study
Theory could result in labelling
could lead to negative preconceptions of people with XYY - self fulfilling prophecy or prejudice
deterministic
suggests XYY is the reason for commiting crimes in those with XYY syndrome, whereas other factors may have influenced
it ignores thaqt people have free will to choose how they behave
Physical featrures cannot be used to classify XYY
anyone can have these physical symptoms, so it cannot be known for definite that someone with these features has XYY
