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Discuss the extent to which genetic inheritance influences behaviour. Free essay! Download now

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Discuss the extent to which genetic inheritance influences behaviour.

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Discuss the extent to which genetic inheritance influences behaviour. essay previewDiscuss the extent to which genetic inheritance influences behaviour. essay previewDiscuss the extent to which genetic inheritance influences behaviour. essay preview


Is human behaviour only influenced by the genes we inherit or do other factors such as our environment of hormonal imbalance play a part.


Unfortunately, a lot of criticism was made about this study due to the ethical concerns about the way the twins used were re-united. The fact that Bouchard used media coverage to obtain participants was also frowned upon because there was no adequate control to establish the frequency of contact between the twins prior to the study. In addition, we cannot assume that twins who are raised together experience the same environment. This is referred to as the ‘’equal environment assumption’’.

The final method used in genetic research is the Adoption studies , which allow the most direct comparison of genetic and environmental influences of behavior. Adopted or foster children usually share none of their genes with their adoptive parents but 50% of the genes with either of their biological parents. Hutchings and Mendick (1975) carried out research on the genetic basis of criminality through adoption studies. They found that if both the biological and adoptive father had a criminal record, 36.2% of sons also had criminal records; if only the biological father had a criminal record, it dropped to 21.4%; if only the adoptive father had a criminal record it dropped to 11.55% and finally to 10.5% if none had a criminal record.

This study is important because it clearly shows the significance of environmental factors. However, despite showing the most direct correlation between genetic and environmental influences on behavior, adoption studies have their drawbacks because adopted children are not representative of the general population. In addition, adoption agencies tend to use selective placement , whereby foster children are placed in families who are similar in as many ways as possible to their natural parents. It therefore becomes difficult to separate the influences of the environment.

However, besides environmental influences, there are other factors that can influence behavior. After Hutchings and Mendick‘s study, more studies were carried out to find other factors that could influence criminal behavior in an individual. Blair et al (1999) looked at the brains of convicted psychopaths. PET scans revealed impairment of the pathways between the amygdala and the frontal lobe. The amygdala is responsible for emotional responses and the limbic system in the frontal lobe for decision making. This impairment therefore has a significant effect on the individual’s moderation of emotions, interaction with others and development of empathy of feelings of remorse. As a result, the individual acts impulsively with no regard for the consequences. This theory is called the Frontal Brian Hypothesis.

In a further study done by the US Federal Bureau of Investigation (FBI-2004), out of their criminal records, 90.1% of apprehended mass murderers were male, as were 82.1% of those arrested for violent crime. This difference was biologically accounted for with the explanation that men posses lower levels of the neurotransmitter, serotonin, which has been linked to antisocial and impulsive behavior. In addition, James Dabbs demonstrated that violent criminals have higher levels of testosterone. These two studies raise the delicate question; ‘’If psychologists can determine that criminals have a biological predisposition towards their behavior, that is, neurochemical imbalance and frontal lobe damage, should courts and governments be more lenient towards them and rethink the policy of punishment for crime?

However, despite all these hypotheses, there still exists John. B. Watson’s (1924) ‘’nurture only’’ side of the debate. His hypothesis was based on the theory that (in paraphrase) should he be given a dozen healthy infants, he could pick one at random and train him to become any type of specialist he selected- a doctor, lawyer, even thief or beggar, regardless of his talents or race of ancestors. It is only recently that the interaction of biological and environmental factors has been considered.

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