2.1, Biological Flashcards
Twin Studies - Lange
- Study of 30 pairs of same sex twins.
- At least one twin in each pair had a known criminal record.
- 10 out of 13 Monozygotic twins both had criminal records whereas only 2 pairs out of the 17 Dizygotic had a criminal record.
Twin studies - Christianson
- Evaluated 3.5k pairs of twins born in Denmark between the 1880’s to early 1900’s.
- If one twin had engaged in criminal activity in MZ pairs, there was a 50% chance the other one would too.
- If one twin had engaged in criminal activity in the DZ pairs, there was a 20% chance the other one would too.
- The correlation showed genetic closeness of the biological relationship played a significant role.
Twin studies, MZ vs DZ
Monozygotic twins develop from a single egg, share all of the same genetic material and are identical.
Dizygotic twins develop from two eggs and share about 50% of their genetic material, about the same as normal siblings. They are also fraternal.
Adoption studies - Crowe 1972
-If the adopted child’s birth parent had a criminal record, there was a 50% chance they would have one too.
If their biological parent did not have a criminal record, there was a 5% chance that they would have one.
Adoption Studies (General Idea)
Reviews the significance of the impact on an individual by the process of nature vs nurture.
Adoption Studies - Nature vs Nurture
If the child is more similar to their birth parent then nature has a bigger impact, if the child is more similar to their adoptive parent then nurture has a bigger impact.
William Sheldon, Somatotypes
Endomorphic- fat and soft, most prone to mental illness.
Characteristics (Sociable)
Ectomorphic - Thin and fragile, most prone to suicidal tendencies.
Characteristics (Introverted and restrained)
Mesomorphic - Muscular and hard, most prone to crime.
Characteristics (Aggressive and adventurous)
Neurochemicals
Neurochemicals may be the reason for criminal actions as certain tendencies are controlled by different parts of the brain that may be affected by an increase in neurochemicals.
- Serotonin
- Dopamine
Jacobs XYY theory
Occurs in 1 out of every 1,000 boys.
Defendants may use it in court to relieve the criminal of some responsibility.
Those with it are able to lead normal lives despite minor physical difficulties such as
-speech problems
-weaker muscle tone
and furthermore, symptoms in babies may include
-delayed motor skills
-emotional/ behavioural issues
-delayed speech problems
Jacobs XYY physical attributes
- Taller than average
- Severe acne
- Skeletal malformations
- mental deficiencies
Raine Et Al (Pre frontal cortex)
Damaged caused to the pre frontal cortex
- loss of control
- inability to modify behaviour
- impulsivity
- immaturity
- emotionally altered which may cause increased aggression.
Adoption Studies - Mednick
Study of 14,000 adopted children.
High proportion of convicted boys birth parents were also convicted.
significant correlation between adopted children and their birth parents.
no relationship in criminal convictions between adopted children and their adoptive parents.
Lombroso
Criminality was something that was inherited rather than the actions of one individual by choice.
Criminals were easily identifiable by their physical features according to each crime by atavistic and savage features such as
Murder - blood shot eyes, hawk like nose, curly hair
Sex offender - thick lips, protruding ears
Theft - Expressive faces, manual dexterity, small wandering eyes.
Phineas Gage
1845, 25 year old Phineas Gage was working as a railroad constructer when he was impaled through his left cheek, brain and out of his skull by a 43 inch tamping iron rod.
He managed to stay conscious enough to look for a doctor.
It instantly blinded him in one of his eyes.
Though his prefrontal cortex was damaged there were no other major physical changes however those who knew him before the incident claimed he was no longer himself.
