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Biology and Genetics.docx

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CRIM 103
Jennifer Wong

The Interaction of Biology and Environment: - Born without inherent capabilities and predispositions - Interact with family, social, cultural circumstances - Nature via nurture - Born with genetic dispositions, but environment plays a role Genetics and Crime (I): Family Studies: - Dugdale (1877): Traced Juke family 1750-1870 - -> 709 descendants, -20% criminal - Farrington’s Cambridge Study (1998) - -> 3 generations of males - -> 83% of boys married girls with criminal records - -> more likely to have criminal children (maybe due to genetics, but also from parent’s behaviour) - Cannot determine relative impact of genetics versus environment Twin Studies: - Monozygotic versus dizygotic twins - Compare twin behaviour to examine genes versus environment - Monozygotic are true twins, completely identical genetic makeup - Dizygotic are fraternal twins, genetically different (not identical) - Higher rates of similar behaviour in monozygotic twins Shared versus Nonshared Environments: - Prenatal and living experiences affecting twins in same versus different ways - Nonshared influences increase with age; shared decrease Concordance: - Degree to which pairs of subjects both show particular behaviour or condition - E.g. 50 pairs monozygotic and 50 pairs of dizygotic twins - -> if 25 pairs of MZ have same IQ score, concordance = 50% - -> if 10 pairs of DZ have same IQ score, concordance = 20% Twin Studies and Criminality: - Raine (1993): reviewed 13 twin studies - -> 52% concordance for MZ, 21% for DZ - Genes predispose; life experiences increase or decrease this risk - -> Jaffee et al. (2005): 1,100 twin pairs - *conduct problems highest for those with high genetic risk and child maltreatment Adoption Studies: - Cross-fostering designs: - -> criminal behaviour of adopted children compared to biological and adoptive parents - Schulsinger (1972): psychopathy in adopted children - Crowe (1974): adoptees with biological, criminal mothers versus biological, non-criminal mothers - If person with criminal parents is not raised by those parents, yet still shows criminal behaviour, strong genetic tendency for crime Denmark Adoption Databank (Mednick, 1984): - - Criminal Biological Parents - Criminal Adoptive - Yes - No Parents - Yes - 24.5% - 14.7% - No - 20% - 13.5% Search for a Crime Gene: - XYY chromosome in “supermales” - -> Jacobs et al. (1965): XYY linked to height, mental retardation, violence - -> Jarvik et al. (1973): XYY in general population = 0.14%; criminal population = 1.9% - XYY not a strong explanatory factor for crime Temperament (II): - “Natural” mood disposition: - -> biological basis - -> appears in infancy, continues through life - -> influenced by environment - Usually studied in infants - -> activity, emotionality, self-regulation 3 Temperament Styles (Thomas and Chess, 1977): - The easy child - -> highly adaptable, easy to get along with - The difficult child - -> initial inversion to new things, don’t like environment changes, bad mood, high intensity of emotional expression - The slow-to-warm-up child - -> low intensity of emotional expression, bad mood Neuropsychological Factors (III): - Neurotransmitters: brain chemicals that transmit nervous system messages - E.g. serotonin (low levels play a role in violence) - Hormones: compounds released by endocrine gland - E.g. testosterone (aggressive behaviours, levels are influenced by environments) - Berton et al. (2006): brain-derived neurotrophic factor (BDNF) in bullied mice - Bullied mice had a dramatic aversion to mice (scared to meet
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