Biological theories
Nature v. nurture
What’s presently accepted?
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Inheritance & environment don’t “cause” but may “predispose”
– Crime is a social definition -- Malum in se v. mala prohibita
– Not all maladaptive behaviors are illegal
Behavior is affected by ...
– Inherited characteristics
– Inherited characteristics, affected by environment
– Environment effects on health (injury, pollution, diet…)
General agreement that biology and environment interact
Sociologists, including criminologists, tend to minimize
biological and psychological factors
– But as we learn more about the human organism, more and
more winds up being explained by chemistry
A trip through the past:
body type (“somatotypes”)
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Sheldon linked physique and temperament
– Endomorph: Soft physique, relaxed and comfort-seeking
temperament
– Mesomorph: Muscled physique, active and assertive
temperament
– Ectomorph: Lean, frail physique, introverted temperament
Gluecks found correlation between mesomorph somatotype
and aggressive/antisocial/uninhibited behavior
Family studies - Goring
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Examined relationship between heredity, environment and
length/frequency of imprisonment
– Heredity  imprisonment?
– Environment  imprisonment?
Findings
– Environmental factors not correlated with imprisonment
 Poverty, broken homes, nationality, birth order
– Biological factors are correlated with imprisonment
 Physical size (smaller, worse off)
 Mental inferiority
 Criminal family members
Criticisms of Goring and family studies
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Failure to adequately measure environmental variables
Current data does not suggest that crime “runs rampant” in
families
Difficult to control for environmental effects within families, as
all are usually exposed to similar circumstances
Twin studies
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Difficult to control environmental variables
– So, control heredity
Fraternal twins: different eggs, different DNA
– Can inherit different biological factors
Identical twins: one egg, same DNA
– Biological factors the same
Look for similarities and differences in behavior
– Similarities between identical twins can be hereditary or
environmental; differences cannot be hereditary
– If behavior of sets of identical twins is more alike than
behavior of sets of fraternal twins, heredity may be important
Studies of identical twins -- Christiansen
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6,000 pairs of male twins
– Male identical twins: 67 pairs where at least one was
registered as a criminal.
 In 36% of these pairs (n = 24) both were criminals
– Male fraternal twins: 114 pairs where at least one was
registered as a criminal
 In 12% of these pairs (n=14) both were criminals
– Higher concordance for serious crimes
Issue: Could higher concordance of behavior for identical twins
be due to a more similar environment?
Twins reared apart
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Similar environments might make identical twins act alike, so
study identical twins reared apart
Grove (32 pairs separated shortly after birth); Christiansen (8
pairs).
– Both found evidence that antisocial behavior can be
inherited
Walters - 1992 meta-analysis of 14 twin studies
– Considered sample size, quality of research design
– Support for hereditary basis to criminality
May be difficult to control for environmental effects
Adoption studies
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Attempt to control for environmental effects
Hutchings and Mednick -- biological fathers appear to influence
boys’ criminality
Boys not
delinquent
Boys
delinquent
Bio. father
Not criminal
69%
51%
Bio. father
criminal
31%
49%
Mednick -- cont’d
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Number of court convictions of biological parents (not adoptive parents)
influences youth criminality, but only for property crimes
Other influencers:
– Socioeconomic status of biological and adoptive parents
– Personality disorders of biological parents
– Number of placements before adoption
– Criminality of biological and adoptive fathers interacts
Issues with adoption studies
– Low sample sizes
– Recent studies found link between heredity and behavior only for
minor and property crime (far more frequent than violent crime)
– Adoptive parents often more law-abiding than general population
Brain chemistry
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Neurotransmitters
– Chemicals that transmit electrical impulses in the brain
– Levels affected by medication, diet, drug use, stress
– Imbalance may promote aggressive or compulsive behavior
 Violence, drug use
Hormones
– Testosterone: Documented role in animal aggression, effects found
in human research
Issues
– Causal order: Aggression may be the cause (not the effect) of high
levels of hormones
– Booth and Osgood study
 Association between testosterone and adult deviancy
 BUT – effect of high levels mediated by social integration
High levels  lack of social integration  aggression
Central nervous system (CNS)
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Brain and spinal cord
Cerebral cortex - outer portion of the brain
Four lobes (frontal,
temporal, parietal,
occipital)
Frontal and temporal lobes
control goal-directed
behavior, impulses and
emotions
CNS and criminal behavior
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Some evidence that abnormalities in the lobes may be
associated with violent and sexual offending
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Frontal dysfunction may be associated with violent offending
Temporal dysfunction may be associated with sexual
offending
Violent sexual offenders may have both dysfunctions
Issues
– Research methodology - no sampling (with a hammer,
everything’s a nail)
– Precise path to offending is unknown
Autonomic nervous system (ANS)
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Controls involuntary
functions: Blood pressure,
heart activity, intestinal
activity, hormone levels
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“Fight/flight” situations: ANS
prepares body to respond
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Blood from stomach to
muscles
Increases respiration
Stimulates sweat
(increases electrical
conductivity of skin)
ANS - continued
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Anxiety (e.g., conditioned fear of being punished for telling a lie)
is basis for lie detection
Anxiety may be the primary socializing agent for children
– They behave properly to avoid anxiety of punishment
Hypothesis that defective response can interfere with
socialization
– Antisocial persons might be more difficult to “condition”, so
they are less likely to fear punishment
Environmental-biological factors:
Drugs and alcohol
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Alcohol in lower doses increases aggressive behavior, especially
in males
Marijuana may reduce but does not increase aggression
Opiates may reduce aggression
– Chronic use may increase aggression
– Withdrawal from opiates may also increase aggression
Methamphetamine, PCP and LSD may increase aggression
– May be especially true for those predisposed to violence
– Police anecdotes about extreme violence and strength
displayed by persons high on Meth and PCP
No direct evidence of effect of cocaine on violence
– Association between violence and areas where rock cocaine is
used (inner cities)
– Note - “rock” cocaine is much more concentrated
Other environmental-biological factors
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Lead in diet may affect brain functions
– May cause hyperactivity and antisocial behavior in children
Head injury with brain damage may cause violent behavior
– Decrease cognitive and social skills
– Headaches and irritability
– Damage frontal and temporal lobes, increasing anxiety,
anger and hostility
Delivery complications correlated with violent offending
– Particularly when parents had psychiatric problems