Genetic factors 16 marker
Genes determine how much of specific hormones involved in aggressive behaviour (such as
testosterone) are produced, how fast they circulate and are responded to. There are two
ways to measure the effect genetics have on aggression and behaviour, the first is
heritability (twin studies) where if genes have a 100% impact on aggression then
monozygotic (MZ) twins will have 100% concordance rates in that behaviour. The second is
studying adopted children, because if they share similar levels to parents its genetic or
adopted parents then it is more the environment influencing aggression.
The MAOA gene is particularly linked to aggressive behaviour, as it regulates the MAOA
enzyme to break down and remove excess amounts of dopamine and adrenaline which then
controls aggression. This is because high levels of these neurotransmitters have been shown
to cause aggression. However, the defective MAOA gene MAOA-L means the enzyme can’t
be produced so these neurotransmitters aren’t broken down, and high levels of aggression
result. This can be seen as populations with a history of warfare have more people than
average with this defective gene.
Research in support for the role of genetics in aggression was conducted by Caspi in 2002.
He found that having the MAOA-L gene doesn’t seem to impact aggression unless the
individual was abused during childhood. This suggests that genetics and nature only play a
role if stimulated by environmental nurture factors. Therefore, a diathesis-stress
interactionist approach should be taken to include both sides of the nature nurture debate
to help more thoroughly explain aggression instead of just using genetics.
Different studies supporting the influence of genetic factors in aggression have different
means of measuring how aggressive an individual is. As some studies use self-reports and
others direct observation which not only are both subject to social desirability bias and lack
validity but also, mean it’s difficult to compare studies and come to general conclusions.
Decreasing internal validity of the role of genetics in aggression.
Another criticism of the role of genetics in aggression is that the majority of studies in
support fail to correctly operationalise and represent violence. This is because a lot of
studies use criminal convictions to measure how aggressive an individual is. However,
violent attacks that they don’t get convicted for are in the majority compared to those they
receive convictions for and some people may be more aggressive but be better at avoiding
convictions then someone less aggressive. Therefore attempting to use convictions to
compare peoples aggression has numerous methodological flaws so can’t be generalised
beyond the study and therefore fails to provide any concrete evidence in support of the role
of genetics in aggression.
Genes determine how much of specific hormones involved in aggressive behaviour (such as
testosterone) are produced, how fast they circulate and are responded to. There are two
ways to measure the effect genetics have on aggression and behaviour, the first is
heritability (twin studies) where if genes have a 100% impact on aggression then
monozygotic (MZ) twins will have 100% concordance rates in that behaviour. The second is
studying adopted children, because if they share similar levels to parents its genetic or
adopted parents then it is more the environment influencing aggression.
The MAOA gene is particularly linked to aggressive behaviour, as it regulates the MAOA
enzyme to break down and remove excess amounts of dopamine and adrenaline which then
controls aggression. This is because high levels of these neurotransmitters have been shown
to cause aggression. However, the defective MAOA gene MAOA-L means the enzyme can’t
be produced so these neurotransmitters aren’t broken down, and high levels of aggression
result. This can be seen as populations with a history of warfare have more people than
average with this defective gene.
Research in support for the role of genetics in aggression was conducted by Caspi in 2002.
He found that having the MAOA-L gene doesn’t seem to impact aggression unless the
individual was abused during childhood. This suggests that genetics and nature only play a
role if stimulated by environmental nurture factors. Therefore, a diathesis-stress
interactionist approach should be taken to include both sides of the nature nurture debate
to help more thoroughly explain aggression instead of just using genetics.
Different studies supporting the influence of genetic factors in aggression have different
means of measuring how aggressive an individual is. As some studies use self-reports and
others direct observation which not only are both subject to social desirability bias and lack
validity but also, mean it’s difficult to compare studies and come to general conclusions.
Decreasing internal validity of the role of genetics in aggression.
Another criticism of the role of genetics in aggression is that the majority of studies in
support fail to correctly operationalise and represent violence. This is because a lot of
studies use criminal convictions to measure how aggressive an individual is. However,
violent attacks that they don’t get convicted for are in the majority compared to those they
receive convictions for and some people may be more aggressive but be better at avoiding
convictions then someone less aggressive. Therefore attempting to use convictions to
compare peoples aggression has numerous methodological flaws so can’t be generalised
beyond the study and therefore fails to provide any concrete evidence in support of the role
of genetics in aggression.
