bio explanation of crime: xyy Flashcards
what does the XYY theory focus on?
the genetic makeup of a person and chromosomal abnormalities due to random mutations
what is a chromosome?
thread like structure made up of DNA found in a cell’s nucleus
how many pairs of chromosomes do humans have?
23
during normal development, what does the 23rd pair consist of?
sex chromosomes
what are the female sex chromosomes?
XX
what are the male sex chromosomes?
XY
what does XYY syndrome involve?
an extra Y chromosome resulting in 47 instead of 46
how often does XYY syndrome involve?
1/1000
what are the characteristics of XYY syndrome?
tall
large teeth/head
acne
curved pinky fingers
lack of empathy
how can XYY lead to criminal behaviour?
behavioural problems including being very active or impulsive and emotional difficulties such as anger and lack of empathy
what is the link between crime and autism/ADHD in XYY males?
the males have an inability to learn via conditioning and cannot respond appropriately to social cues which could lead to antisocial behaviour
what is a strength of XYY syndrome as an explanation of crime (PEE)?
- stockholm
a strength of XYY syndrome as an explanation of crime is supporting evidence from Stockholm. they found that there was a significant increase in the number of convictions in a group of males with XYY compared to general incidences of crime in general population. therefore, this supports the positive correlation between criminal behaviour and having XYY.
what is a strength of XYY syndrome as an explanation of crime (PEE)?
- Jacobs et al
a strength of XYY syndrome as an explanation of crime is supporting evidence from Jacobs et al. they found that 15/1000 males in prison have XYY in comparison to the 1/1000 in the general population. therefore, this supports the concept that males with XYY are overly aggressive and lack empathy which is why there is a greater percentage in prison. however, Theilgaard took blood samples of 30,000 males and found those with XYY did have lower intelligence and were more aggressive however not all crimes are aggressive and not all aggression is criminal suggesting a minimal link.
what is a weakness of XYY syndrome as an explanation of crime (PEE)?
- criticism
a weakness of XYY syndrome as an explanation of crime is that it lacks internal validity. this is because the research is correlational so only a link can be found between an extra Y chromosome and crime making it hard to establish a cause & effect. therefore, a third variable could be the reason for the crimes, such as socioeconomic background or genetics e.g raised testosterone levels. furthermore, Re & Birkhoff carried out a review study and found ‘no statistical evidence that an XYY man is predisposed just because of his genotype to aggressive behvaiour’.
what are the applications of XYY being an explanation of crime (PEE)?
a strength of XYY syndrome as an explanation for crime is the practical applications. for example, 25% of the syndrome can be identified at birth, so if this is screened for early, criminality can be addressed. therefore, treatments such as therapy could be put in place to prevent criminal behaviour developing and this keeps the individual and society safe, as well as preventing the label arising.
