Biological theories of criminality Flashcards
What are biological theories
They focus on the idea that physical characteristics make some people more likely to commit crimes than our genetic makeup
What are genetic theories
The theory that criminality runs in our genes
What are physiological theories
The theory that someone is a criminal just from their physical characteristics or appearance
What are chromosomes
tiny strands of DNA that carry individual genes for every characteristic.We have 46 in total, but 23 pairs
What are genes
units of DNA which code for one or more characteristics and are inherited from a persons parents.
What are the 3 types of genetic theories
1- Twin studies
2- Adoption studies
3- Jacob’s XYY study
What are the two types of twins
1- Monozygotic (identical)
They have a shared placenta, come from 1 egg and share 100% of DNA
2- Dizygotic (non-identical)
They have separate placentas, come from separate eggs and share 50% of DNA
What are concordance rates?
the probability that if one twin has genetic traits, the other twin will too
What did Johannes Lange study (1929)?
He investigated 13 MZ wins and 17 DZ twins to see how likely it was that pairs of twins had either both served time in prison or just one twin.
What was the findings of Lange?
He found that 10/13 MZ twins had both served time in prison.
Only 2/17 DZ twins had both served time in prison.
What did Christiansen study (1977)?
He investigated the offending behaviour of 3586 twin born between 1881 and 1910 in Denmark to find what they had both done or just one twin had done
What were the findings of Christiansen?
MALE- MONOZYGOTIC- 35%
MALE- DIZYGOTIC- 13%
FEMALE- MONOZYGOTIC- 21%
FEMALE- DIZYGOTIC- 8%
What is the problem with twin studies?
They suggest that criminal behaviour is to do with genetics.
However if crime was really fully genetic the concordance rates between twins would be 100% for monozygotic twins as they share all their DNA, but they aren’t 100%.
What are adoption studies?
This is to find out if adopted children change their behaviour depending on if they’re with their biological or adopted parents and if biology or the environment is more influential on the children’s behaviour. THEY DON’T NEED TO NECESSARILY INVOLVE TWINS- DON’T GET THESE MUDDLED IN THE EXAM.
What did Mednick et al study (1975)?
