We have discussed individual differences inintelligence. The unit also served to introduce us to other units in this course. You can now explain normal probability curve, identify different forms in which inte1ligence comes into play. In addition, you can describe the concept of IQ and explain its defect. Right now, you will study another unit that is very topical and interesting; explaining behaviour-genetic influences and environmental influences. We will now consider influences on behaviour. Let us look at what other content you should learn in this unit as specified in the objective below.
By the end of this unit, you should be able to: describe some of the main psychological influences on human behaviour.
3.0 MAIN CONTENT
3.1 Behaviour – Genetic Influences
One of the longest running debates in psychology is the ‘nature versus nurture’ debate. This relates to the question of whether behaviour is best explained by reference to genetic or to environmental factors. Note that at times the issue divides the academic community, with proponents of both schools of thought providing evidence supporting their own viewpoint and challenging that of their opponents.
The question is important for a number of reasons. If it is possible to prove that a person’s genes predominantly determine certain aspects of behaviour, then there is little point in trying to change people by using external influences. Let us cite an example to ensure clear understanding. If intelligence was found to be almost entirely determined by genetic factors, then there would be little point in spending billions of naira on providing a good education for those who are low in intelligence. To do so would be a ‘wasted effort, as any such attempts would be unproductive.
Similarly, if genetics were found to largely determine criminality, there would be profound implications regarding how society deals with those who exhibit criminal tendencies from an early age. If one were to believe in’ such a viewpoint, then one would want to adv6cate that such individuals be incarcerated at an early age and not be released. Punishment and rehabilitation would presumably be a waste of time because such individuals would be unable to overturn the powerful effects of their genetic make-up.
While it is true that a person’s genetic make-up does affect their behaviour, it is rarely in such an absolute way as implied by the examples above. It is important for you to note that these days, psychologists rarely talk about behaviour being determined by either heredity or the environment. Most psychologists would accept that any behaviour results from the interaction between genetic factors and the environment.
SELF-ASSESSMENT EXERCISE 1
1. a. Explain what you understand by nature.
b. What is nurture?
Let us continue our discussion. Now, we need to consider how genetic influences might affect behaviour.
Every human being comes into this world with a genetic make-up. Note that this is the blueprint for the individual’s passage through life and as originating from his or her parents. When a baby is first born, relatives often look to see whether the child looks more like the mother or father. Each new child results from the combination of elements from both the mother and father. The human reproduction system ensures that, with the exception of identical twins, there are no two genetically identical people in the world. You must note that, although there can be nothing in the child that has not come from the mother or father, each child will be genetically different.
If you think about a large family with a number of brothers and sisters, each family member may share common characteristics but there will also be identifiable differences between each individual. I know you are eager to know why this is so: This may be partly due to the different genetic make- up of each individual, but also partly because each child will have slightly different experiences as he/she grows up.
Let us consider the example of criminality. You may have your own view as to whether or not crime runs in families. The evidence suggests that children born to criminal parents run an increased risk of becoming criminals themselves. It is to be noted that while crime may run in families, this does not necessarily prove that genetics is the correct or the only explanation. It may be that criminal parents instill values in their children that make them more likely to adopt a criminal lifestyle as they grow up. While most parents would punish their child if they committed a criminal act, criminal parents may encourage or reward their own child for following in their footsteps.
Those who wish to argue for the importance of genetic factors often look to the study of twins for evidence to support their viewpoint. There are two distinct types of twins, that is identical and non-identical. As the name implies, identical twins are genetically identical and result from a splitting of the zygote around the time of conception. Such twins are referred to as monozygotic or MZ. Non-identical twins are the result of two different eggs being fertilized by two different sperms around the same point in time. Non-identical twins are also known as dizygotic or DZ. Note that although they are conceived at the same time, they are genetically no more similar than brothers or sisters conceived and born at different times. Because they are genetically identical, MZ twins will always be the same sex, whereas DZ twins are sometimes of the same, but sometimes of different sexes. You deserve commendation for active participation in our discussion. Let us continue by attempting this question.
SELF-ASSESSMENT EXERCISE 2
Have you ever come across any set of twins? What were your impressions?
We must now go on. If genetics is important, then we would expect identical twins to be more similar than non-identical twins. For research purposes, the ideal study would be to examine pairs of twins who were separated from teach other early in life, to see whether they still ended up with similar behavioural characteristics. If this was the case, it might be suggested that genetic Influences are perhaps more important than those of the environment. Where such research has been carried out it shows consistently that identical twin pairs do often end up more similar that non-identical twin pairs, even when they have been raised in different environment. Where such research has been carried out it shows consistently that identical twin pairs do often end up more similar that non-identical twin pairs, even when they have been raised in different environments. Research of this kind would lead us to believe that genes have some influence over behaviour, but this influence is not all embracing. You must note that our genes set some limits on what can be achieved, but the exact result will be determined by our life experiences. This can be illustrated by research on identical twins. We saw earlier that identical twins are of great interest to psychologists because they can help us unravel the relative contribution of genetics and the environments.
Let us now consider crime and genetics. Dilalla and Gottessman (1990) reviewed some 40 years of twin studies and claimed to have found some evidence to support the view that criminal behaviour might have a genetic component. You must note that criminal behaviour covers such a vast array of actions that there can be few people who have never committed a criminal act during their lifetime.
3.2 Determinants of Editorial Subject
We saw in the previous section that genetics can play an important role in understanding human behaviour. We also noted that genetics alone can never fully explain why people behave as they do. It is important for you to note that while all individuals enter the world with a genetic make-up, they are not raised in a social or environmental vacuum. If we are to fully understand why people behave as they do, we need to consider both their genetic make-up and the environment in which they are raised.
From the moment of conception, the developing child is subject to all sorts of environmental influences. Even in the womb, the child may develop differently if the mother smokes, takes drugs or is ill while pregnant (Alhassan, 2000). Once born, the baby will be subject to a vast array of environment influences that will help to shape him/her. As this writer explained elsewhere (Alhassan, 1983:450), environment is the aggregate of all external and internal conditions affecting the existence, growth, and welfare of organisms in general and the child in particular. A child’s environment commences from within her mother’s womb. Thereafter, a child experiences a social environment, a physical environment, an economic environment, and in fact, a political environment. Of course the cultural environment is all-embracing. Both heredity and environment contribute to an individual’s intelligence.
It is obvious that the environment can exert a powerful influence on behaviour but when it comes to explaining our own behaviour, humans are not always willing to accept this fact. If you were asked whether you are an independent sort of person, or whether you simply go along with the crowd, you would probably say that while you are influenced by others to some extent, you are still capable of independent thought and decision making. Yet social psychology (which we discussed in unit 4) provides ample evidence of the powerful effects that social situations can have.
Let us cite an example. Police Officers will tend to presume that the vast majority of people who are arrested and questioned might initially deny the offence but may eventually confess to the crime. It may never occur to the officer concerned that if a person does confess, this results from the powerful situational environmental forces to which the suspect is subjected.
In this unit, you have learnt influences on behaviour. You have therefore learnt the important role of genetics in all human behaviour but genetics rarely has a direct or total influence. We also learnt that the environment in which people are raised must be considered.