BIOLOGICAL THEORIES OF CRIME : GENETIC Flashcards
what are the three genetic biological theories of crime?
Jacob’s XYY
twin studies
adoption studies
what is Jacob’s XYY about?
chromosomal abnormality
around how many new borns have an extra Y chromosome?
1/1000
how many times more likely is someone with XYY likely to be in a prison population?
10x more likely
why are men with an XYY chromosome more likely to be found in a prison population?
because the extra Y chromosome makes them more masculine, so they produce more testosterone
Jacob et al found what to support his theory?
a link between aggression to violent behaviour
what is another strength of Jacob’s XYY study?
we can see they are more represented in the prison population
what did Jacob’s XYY study not look at, which is a limitation?
didn’t look at psychological, environmental and social factors
who found that XYY men were not linked to aggression?
Thielgaard
what did Theilgaard find that is a limitation of Jacob’s XYY study?
that XYY men were not linked to aggression
what year did Theilgaard discover there was no link?
1984
what are the two types of twins in twin studies?
monozygotic that come from one egg and dizygotic which comes from two eggs
what is controlled in twin studies?
the environment as they are equal
who tested on 30 same-sex twins?
Lange
how many MZ twins were in Lange’s study?
13
how many DZ twins were there in Lange’s study?
17
how many of the MZ twins were both criminal?
10/13
how many out of the DZ twins were both criminal?
2/17
what does the statistic of twin studies show?
crime is genetic and it is hereditary
what is the chance of one twin taking part in criminal behaviour if they are MZ?
50%
what is the chance of one twin taking part in criminal behaviour if they are DZ?
20%
why is twin studies being in a controlled environment a strength of the research?
because the researchers didn’t have to manipulate any variables, making it natural reducing investigator/researcher bias
what is a limitation of twin studies?
small sample size
what does small sample size effect for twin studies?
population validity as it’s finding cannot be generalised to all people
what did Lange’s study not look at that is a limitation of it?
didn’t look at social factors such as friendship groups or social media that they could be affected by individually
research from adoption studies show…
adoptee w/ crim parent is more likely to commit crime
out of all adoptees born from a crim parent, who is most likely to participate?
boys
out of all types of crime, what are adoptees born from a crim parent most likely to commit?
property crime such as vandalism or burglary
what did the study in Iowa prison show?
higher rate of criminal adoptees to commit crime
what research is there to support adoption
studies?
Mednick et al
Hutchings and Mednick
what did Mednick et al find to support twin studies?
adopted parents number of convictions didn’t affect the adoptees chance of getting into crime but the biological parent’s number of convictions did
what did Hutchings and Medick find?
boys were criminal convictions were aggressive due to genetics
