Biological explanations: Genetic and neural 16 marker
Firstly, twin and adoption studies suggest that genes predispose offenders to crime.
Christiansen found a concordance for offender behaviour in 35% for identical twins, and 13%
for non-identical twins out of more than 3500 twin pairs, there were slightly lower rates for
females.
Adopted children with a criminal record mother had a 50% risk of having a criminal record at
18. The adopted children with no criminal mother had 5%.
There are candidate genes such as the MAOA gene regulates serotonin, and this is linked to
aggressive behaviour. THE CDH13 gene is linked to substance abuse and ADHD. A study
found that 5-10% of violent crime in Finland was linked to these genes.
The diathesis-stress model suggest that offending occurs due a combination of genes and
the environment for example being raised in a dysfunctional environment or having criminal
role models.
Neural explanations suggests that there may be neural differences in the brains of offenders
and non-offenders. Much of the evidence in this area has involved individuals diagnosed
with antisocial personality disorder formerly referred to as psychopath). Antisocial
personality disorder (APD) is associated with lack of empathy and reduced emotional
responses. Many offenders have APD. Raine found an 11% reduction of grey matter volume
in the prefrontal cortex (which regulates emotional behaviour) of people with APD
compared to a control group.
Lastly, mirror neurons (empathy) may not always be turned on. Keysers found offenders only
showed empathy when asked. APD individuals do experience empathy but have. ‘switch’ to
turn it on and off. This is different from normal brains where empathy is always turned on.
One limitation of the genetic and neural explanation for offending is twins are assumed to
have equal environments. For example, MZ twins look identical, and so people (especially
parents) treat them similar which in turn affects their behaviour. This suggest that there are
higher concordance rates for MZ’s because they are treated similarly. This means the twin
findings lack validity.
One strength is that there is support for the diathesis-stress model. 13,000 Danish adoptees
were studied when neither the biological nor adoptive parents had convictions, the
percentage of adoptees that did was 13,5% (which is quite high). This figure rose to 20%
when either of the biological parents had convictions, and 24.5% when both adoptive and
biological parents had convictions. This shows that genetic inheritance plays an important
role in offending, but environmental influence is clearly also important, providing support
for the diathesis-stress model of crime.
Another strength is that there is support for the link between crime and the frontal lobe.
Research into people with frontal lobe damage (including prefrontal cortex) found evidence
Firstly, twin and adoption studies suggest that genes predispose offenders to crime.
Christiansen found a concordance for offender behaviour in 35% for identical twins, and 13%
for non-identical twins out of more than 3500 twin pairs, there were slightly lower rates for
females.
Adopted children with a criminal record mother had a 50% risk of having a criminal record at
18. The adopted children with no criminal mother had 5%.
There are candidate genes such as the MAOA gene regulates serotonin, and this is linked to
aggressive behaviour. THE CDH13 gene is linked to substance abuse and ADHD. A study
found that 5-10% of violent crime in Finland was linked to these genes.
The diathesis-stress model suggest that offending occurs due a combination of genes and
the environment for example being raised in a dysfunctional environment or having criminal
role models.
Neural explanations suggests that there may be neural differences in the brains of offenders
and non-offenders. Much of the evidence in this area has involved individuals diagnosed
with antisocial personality disorder formerly referred to as psychopath). Antisocial
personality disorder (APD) is associated with lack of empathy and reduced emotional
responses. Many offenders have APD. Raine found an 11% reduction of grey matter volume
in the prefrontal cortex (which regulates emotional behaviour) of people with APD
compared to a control group.
Lastly, mirror neurons (empathy) may not always be turned on. Keysers found offenders only
showed empathy when asked. APD individuals do experience empathy but have. ‘switch’ to
turn it on and off. This is different from normal brains where empathy is always turned on.
One limitation of the genetic and neural explanation for offending is twins are assumed to
have equal environments. For example, MZ twins look identical, and so people (especially
parents) treat them similar which in turn affects their behaviour. This suggest that there are
higher concordance rates for MZ’s because they are treated similarly. This means the twin
findings lack validity.
One strength is that there is support for the diathesis-stress model. 13,000 Danish adoptees
were studied when neither the biological nor adoptive parents had convictions, the
percentage of adoptees that did was 13,5% (which is quite high). This figure rose to 20%
when either of the biological parents had convictions, and 24.5% when both adoptive and
biological parents had convictions. This shows that genetic inheritance plays an important
role in offending, but environmental influence is clearly also important, providing support
for the diathesis-stress model of crime.
Another strength is that there is support for the link between crime and the frontal lobe.
Research into people with frontal lobe damage (including prefrontal cortex) found evidence
