FORENSICS - Biological explanation of offending behaviour

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  • Biological explanation of offending behaviour
    • Atavistic form
      • Cesare Lombroso - 1876 - said in book that offenders possessed similar characteristics to lower primates - could explain their criminality
        • created 4 more editions of this books
      • Turvey (2011)  - identifies 18 different characteristics that make up the atavistic type
        • basic assumption: innate psychological make-up of the person causes them to be a criminal
      • Empirical evidence
        • Lombroso based theory on his post-mortem exams and study the faces of living criminals
          • he made precise measurements of skulls and other psych characteristics (anthropometry)
        • he examined 50,000 bodies
        • in particular study 383 convicted Italian criminals - 21% had just one atavistic trait, 43% had at least 5
      • Environmental influences
        • Lombroso realised it was probably not just one characteristic
          • inherited atavistic form interacted with a persons physical and social environment
        • in a later book, he distinguished between 3 types of criminals:
          • born criminals - atavistic type; 'throwbacks' identifiable from their physical characteristics
          • insane criminals - suffering from mental illness
          • criminaloids - large general class of offenders, mental characteristics predisposed them to criminal behaviour (certain physical / social environments)
      • Valla - 36 college students rating photos for criminality (additional group rates attractiveness). Criminals averaged 4.5 vs. 8.85 for non-criminals. No gender diff, but women rated rapists lower than non-crims on average, men did not.
      • suggests facial characteristics may be linked to criminality
        • epigenetic (tough environment may be linked to features)
        • may just be their facial expression
        • some link to personality - largely genetic
        • less attractive children will be treated differently
          • reactive gene environment interaction eg aggressive features -> hostile reaction from others
            • wrong perception on how to treat people
    • Somatotypes
      • criminal types based on body types ('soma')
      • proposed by Kretschmer (1921) based on studies from 4,000 criminals
      • leptosome or asthenic - tall and thin; petty criminals
      • athletic - tall and muscular; crimes of violence
      • pyknic - short and fat; deception and sometimes violence
      • dysplatic or mixed - more than one type; crimes against morality (prostitution)
    • Evaluation of Lombroso
      • brought science to crime
      • sample sizes - didn't use women, didn't have a non-criminal control group, people with mental health problems included - not necessarily criminals
      • somatotypes  based on scrutiny not fact
      • Sheldon (1949) - 200 young adults, difference in delinquents and non-dels in terms of body type (dels = mesomorph)
    • Genetic
      • investigating the genetic connection:
        • twin studies
          • Coccaro (1997) - almost 50% of the variance in aggression could be explained by genes
          • comparing concordance rate (% of matching) between MZ and DZ twins
          • may have had different upbringing - MZ twins treated same = similar behaviour
          • Brunner - study of aggressive dutch family - missing MAOA gene. Gene regulates neurotransmitters leading in particular to low levels of serotonin (linked to aggressive behaviour)
            • since then, 'weak' variant of the MAOA gene has been linked to violent offenders, BUT 40-50% of population had that gene
          • Brunner research suggests diathesis stress model - genetic vulnerability
            • Caspi (2002) - used data from longitudinal Dunedin study that followed 1,000 people when they were babies in 1970s. Caspi assessed anti-social behaviour at age 26, found 12% of those men with low MAOA gene had experienced maltreatment when they were young but were responsible for 44% of violent crimes
          • CDH 13 gene - codes for a membrane protein, but associated with ADHD and other impulsive control problems
          • Finnish study linked CLD 13 and Cadherin to violent behaviour, but authors stated that there were probably many other genes involves
        • family studies
          • could be SLT
        • adoption studies
          • generally, adoptees show a closer correlation than adults, when they often show correlation with biological parents
          • Crowe - 50% of adopted children whose biological mother had a criminal record also had a criminal record by the age of 18. Compared to 5% in the control group (adopted children without criminal parent)
          • some adoptive parents may treat children differently if they know their background
          • criminal mothers may have done things while they were pregnant - doing, drinking, drugs etc
            • in utero differences in behaviour
        • direct inspection of genome
      • genotype - tells us our genes (code). phenotype - characteristics - dependent on environmental factors
      • case of Tony Mobley
        • 1991 murder of pizza store manager, sprees of armed robberies. Claimed he should avoid death penalty bc he was 'genetically predisposed' to crime
          • he was economically privileged, no family history of sexual or physical abuse. Researchers found some people in family responsible for acts of violence from serious crime (murder / ****) to abuse and alcoholism
      • Evaluation (A03)
        • some adoption studies only show marginal increase for genes over environment
        • fail to account for non-violent crimes eg. online fraud / theft. MAOA gene = aggression
        • unlikely that criminality is inherited. Could be meditated via. personality traits, addiction, problems with stress response
        • problems for legal system if deterministic viewpoint taken

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