Criminal Behaviour Biological Explanation: Inherited Criminality

Biological Exp: Inherited Criminality

Certain individuals have a genetic predisposition to commit crime. Lombroso introduced one of the earliest theories of criminal behaviour; claiming all criminals possessed similar characteristics to lower primates. Atavistic Type Narrow sloping brow Ears of unusual size Nose twisted or flattened = THIEVES Nose beak-like = MURDERERS Long arms Extra fingers or toes A nurture rather than nature view One of the first attempts at explaining criminal behaviour, however lack of scientific evidence to support claim. Through Lombroso it gave the opportunity for other psychologists to begin researching possible causes of criminal behaviour. Galton suggested 3 basic research methods to study interaction between nature vs nurture; family, twin and adoption studies.

Family studies;Investigating family history

Farrington et al. (2001) Investigated offending across 3 generations 1,395 US families Similar to UK findings it reported high concentration of offending in families Less than 140 families accounted to more than 40% of all arrested people Crime concentrated in certain environment

Thornberry et al. (2009) Children more likely to use drugs or commit delinquent behaviour if their parents had history of anti-social behaviour However this was affected by level of contact Nurture rather than nature

Evaluation of Family Studies

Thornberry et al. suggested that it was mostly related with nurture in which the child had by level of contact Difficult to separate the effects of genes or environment In lab - they can control a variable, but not possible in real world Cannot split up families to observe effects of environment = Ethically & legally impossible Galton suggested, nature has provided the basis for such experiment in the shape of "Twins Studies"

Twin Studies

Most Twin studies rely on studying twins raised in same family environments MZ twins share 100% of their genetic make-up DZ twins share 50% of their genetic make-up A researcher could compare similarity between sets of MZ twins to DZ twins for trait 'Aggression' and finding MZ twins are more alike Extra concordance be due to genetics rather environmental factors Concordance: used to estimate heritable traits, i.e; Aggression 

Raine (1993)Reviewed research on delinquent behaviour of twins and found 52% Concordance for MZ twins compared with 21% for DZ twins.31% DifferenceMcGuffin & Gottesman (1985)MZ twins 87% concordance rate for aggressive and antisocial behaviour, while DZ twins 72% concordance rateAlthough could be argued that its more nurture because it shows both with high concordance

Evaluation of Twin Studies

It can suggest that genetic component and criminal behaviour have some similarities and thus reinforce into stating that genetics which MZ twins share are more likely to manifest the same personality traits, i.e; criminal behaviours But also having higher concordance rate for aggressive and anti-social behaviour A problem of twin studies is that it shows a correlation but no cause and effect Nature: Often reliant upon random mating; however if individuals choose a partner who is similar to themselves (same traits) then DZ twins may share more than 50% of their genetic make-up Nurture: May not fully separate genes from environment; it is assumed MZ twins and DZ twins are raised in similar environments. However, MZ twins are treated more similar than DZ twins, think teachers and peers Can be ignorant of interaction between genes and environment

Adoption Studies

In order to attempt to separate effects of genes and their environment, researchers have conducted adoption studies Focusing upon criminal records of individuals in comparison to their criminal records of both biological (genetics) parents and adoptive (environment) parents

Hutchings & Mednick (1973)Reviewed over 14,000 adoptions in Denmark > Culture Biassignificant positive correlation between criminal convictions of biological parents and adopted sons > Only Correlation & NO cause and effect + Only male/Gender BiasRhee & Waldman (2002)Genetic component - 40% Environmental component - 60%Outweighing nature

Evaluation Adoption Studies

Bohman (1995) found there was more chance of criminality when there was a genetic risk factor together with environmental risk factor Environment clearly seemed to have its most marked effect on children who might already been genetically vulnerable Bio + Adop parents w/ Crim record: 40% Bio + Adop parents w/out Crim record: 3% Bio w/ Crim Rec + Adop w/out: 12% Bio w/out + Adop w/ Crim Rec: 7% Key findings link shows a high nature to having criminal behaviour.

Gender Differences; An aggressive antisocial behaviour are more heritable in girls than boys, as we can link through Denmark study that it actually has Gender-Bias. When adoption took place; Children may be exposed to their biological parents aggressive environment before being adopted. Cannot fully separate genes and environment. Similarity to biological family; Children are often adopted into a family as similar to their own biological family, creating it even more difficult to separate genes from environment. Although it may show correlation to having biological and adoptive parents with criminal records, it doesn't show any cause and effect.

The Criminal Gene

What is the MAOA gene? Gene responsible for producing the enzyme monoamine oxidase A (MAOA) has been associated with aggressive behaviour. MAOA is responsible for breaking down 3 neurotransmitters: Noradrenaline, Serotonin and Dopamine.

Brunner et al. Netherlands family, many men had history of extreme violence. One man raped his sister + another tried run over his boss. Only men seemed to have such violence nature. Analysed X chromosomes of 28 members of family & found marker on X chromosome present ALL violent men but not non-violent men. Marker linked to one particular gene responsible for MAOA production. Also found excess levels all 3 neurotransmitters in urine of men.

Evaluation of Brunner et al.

Brunner's findings however are unlikely to have a causal relationship between gene & aggressive behaviour. Some influence , but the shared behaviour amongst the men in family be better explained by shared criminal behaviour. Modern understanding of genetic influence no longer proposes one or even few genes on their own will determining criminal behaviour; through male dominance trying to 'man-up'.

Epigenetics

Often explained through environmental experiences activating dormant genes, changing them through interaction. Process by which it can often be explained as "Software Genes", developing and regulating expressions of genes with an ability to turn 'on/off'. Genes contain certain structure of functionality which need further instructions through environmental triggers, i.e. "Switch-like" chemical that may create aggression and link with possible antisocial behaviour.

Implications of an epigenetic explanation; Anti-social behaviour is 'passed down' several generations, i.e. we may have particular family history of antisocial behaviour. However may not be due to genetics but possibly an ongoing cycle of abuse which alters the expressions of genes - the epigenetic effect.

Capsi et al.

Studied 1,000 males from babies to 26 yrs. old and how antisocial behaviour of participants assessed when they were 26 yrs. old Investigated each participants MAOA genotype and experiences of maltreatment. Found those had low-activity MAOA and had experienced maltreatment = more likely to commit anti-social behaviour.  Comparison those with low activity MAOA but not experienced maltreatment, were not likely to commit such offence. Suggests an interaction between certain genes & environmental stresses, i.e. a diathesis-stress: how nature & nurture contribute to genetics. Cannot confirm maltreatment alters expressions of MAOA gene, 

Evaluation & Conclusion; There's evidence to suggest criminal behaviour does have genetic components and could be suggested from simple family studies where crime appears and thus more likely to run in families with detailed investigations into certain criminal genes. Potential treatment; Genetic modification/engineering when child, be creating various ethical issues and therefore rather focus on the possibilities to changing the environment of the individuals.