genes Flashcards
what is the role of twin studies
Corroco found that MZ twins had a concordance rate of 50% whereas DZ twins had 19% concordance rates.
DZ twins share 100% same genes, DZ share 50% same genes.
Twins should share same environment therefore have similar concordance rates.
what is the role of adoption studies
help untangle the relative contributions of environment and heredity in aggression.
-there is a positive correlation between adopted children being aggressive and their biological parents being aggressive individuals
evaluation supporting genetic effect on aggression
-a study over 14,000 adoptions in Denmark found that a significant number of adopted boys with criminal convictions had biological parents with convictions for criminal violence swell, providing evidence for genetic effect
what is the role of MAOA gene
an enzyme that regulates the metabolism of serotonin in the brain.
if you have dysfunction in the production of the enzyme, (leads to MAOA-L) more serotonin is released in the synapse causing serotonin to be over reactive, leading to more aggression.
MAOA-L is also known as the warrior gene, which is found to be common in populations where there is history of warfare
-1/3 of the pop. in western populations have this low-acitivity version
what is supportive eveidence genetic factors
-brunner, did a study family of 28 males in the Netherlands.
He found that there were large amounts of neurotransmitters in the urine, showing that the short variant (MAOA) was stopping them from processing the neurotransmitters, which increases aggression.
Showing that short MAOA leads to more aggression
-however it is ideographic, on a case study of family shouldn’t generalise
-nature nurture debate, they grew up all together with environmental factors being more aggressive in life.
weaknesses of evidence for genetic factors
- reductionist, ignore environmental factors, SLT etc, which have valid explanations.
- deterministic, says if you MAOA-L you are going to be aggressive, thus no free will.
- hard to measure aggression, its hard to operationalise variables of aggression in experiments.
