What is a candidate gene?
A gene chosen for investigation because it may contribute to a behaviour or trait.
What do twin studies compare?
Concordance rates between MZ and DZ twins to estimate genetic influence.
What did Lange (1930) find?
10 of 13 MZ co-twins were also imprisoned, compared with 2 of 17 DZ co-twins.
What does an adoption study try to separate?
Genetic influence from environmental influence by comparing biological and adoptive relatives.
Which genes did Tiihonen et al. (2014) investigate?
MAOA and CDH13, both linked with severe violent offending in their Finnish sample.
What is the diathesis-stress model?
The idea that biological vulnerability increases risk most when combined with environmental stressors.
What did Mednick et al. (1984) conclude?
Both biological and adoptive family risk mattered, with the highest conviction rate when both were present.
Why is the prefrontal cortex relevant to offending?
It supports impulse control, planning, decision-making and emotional regulation.
What did Raine et al. (1997) find?
Murderers in their sample showed reduced prefrontal activity and atypical activity in other emotion-related brain regions.
Why should biological explanations not be deterministic?
Risk factors change probabilities but do not make offending inevitable; environment and individual choices still matter.