The nature versus nurture debate is one of the most convoluted in the field of psychology. In the 17th century, a French philosopher, René Descartes posited that "we all, as individual human beings, have certain innate ideas that enduringly underpin our approach to the world" (Crawford, 1989 p 64). The use of the terms "nature" and "nurture" henceforth has referred to the roles of heredity and environment respectively in human development. Some scientists believe that human beings behave as they do in response to genetic predisposition. This is known as the nature theory of human behavior and is the view espoused by naturalists (Scott, 1995). Other scientists think otherwise; that people think and behave in certain ways because they are taught to do so. This is known as nurture theory of human behavior and is the view of empiricists. Presented in the paper are the theories of nature vs. nurture, elucidation of perception, intelligence and personality within the debate. In addition, the paper discusses eevidences in favor of nurture and the influence of environment on behavior and morality. In exploring the nature versus the nurture debate, the writer presumes that nature endows human beings with inborn abilities and traits while nurture takes these genetic tendencies and molds them as humans learn and mature.
According to naturalists, personality is natural. This group believes that personality is a result of evolutionary process. Human beings, it believes, inherit behaviors due to a complex interaction of genes. As such, genes control their behaviors. They believe that form and characteristics measured with personality tests remain stable throughout human life. They further believe that human beings may sharpen their types or personality but can never change them altogether. Darwin's Theory of Evolution led naturalists such as George Williams, William Hamilton, and many others to the idea of personality evolution. They proposed that physical organs and personality is a result of natural selection (Herschkowitz, 2002). Human beings do as their genes dictate. In support, Steven Pinker (2004) includes conservativeness, religiousness and liberalism as gene related traits. William Paley, in agreement, believes cognitive capabilities, temperaments, and cheating behaviors are inheritable.
There are however various assumptions about nature. Evolutionary psychologists believe that behaviour is a result of natural selection in the environment of evolutionary adaptation (EEA). Interpersonal attraction therefore can be explained as a consequence of sexual selection - men and women select partners who enhance their reproductive success (Crawford, 1989).
Arguments for the supremacy of nurture posit that personality is nurtured. This group argues that one does not get personality from inheritance. They argue that the mind is a blank slate at birth. The definition of nurture has extended to influence of development that emanates from prenatal, parental, peer influence and extending to the role of media, marketing and socio-economic status (Scott, 1995). They dispute that types and characteristics measured with personality tests change incessantly throughout one's life. Harvard psychologist B. F. Skinner's, experiments, produced birds that could dance and play tennis. Today, known as the father of behavioral science, Skinner ultimately went on to prove that human behavior could be conditioned in much the same way as animals. If environment did not play a part in determining an individual's traits and behaviors, then identical twins should be the same in all respects, even if reared apart. However, a number of studies show that they are never exactly alike, even though they are remarkably similar in most respects (Michaels, 2001).
Assumptions about nurture are also present. Radical psychologists such as Skinner and Watson, for instance, claim that all behaviour can be described in terms of experience alone. Skinner (1957) suggested that acquisition of language by a child could be explained entirely in terms of rewards and shaping. The double bind theory of schizophrenia, for instance, suggests that schizophrenia developed in children who frequently received contradictory messages from their parents.
Nature vs. Nurture - Perception
Two main theories of perception are advanced to explain the debate about nature versus nurture. Gibson (1979 as cited by Cardwell and Flanagan, 2004. P 262)  argued that perception is innate because the sensory array is sufficiently rich in information for perception to take place without any additional cognitive input. Gregory (1972) on the other hand pointed to the ambiguous and fragmentary nature of most sensory input, which must thus rely on expectations (derived from experience) to complete the perceptual process (Michael, 2001).
Intelligence and Personality- Nature vs. Nurture
Evidence in favor of nature has been reinforced by hypothesis on IQ that has been tested on twins and adoptees. Monozygotic twins raised apart are highly similar in IQ (0.74), more so than dizygotic twins raised together (0.6) and much more than adoptive siblings (~0.0) (Crawford, 1989). In other studies done in Harvard, identical twins reared separately exhibited likeness in the timing and pattern of development and maturation. Further was a likeness in some of the foundations of temperament and behavior, from sensitivity to activity to emotional response (Westen, 2002). This denoted that the personality of twins was influenced by their genetics than the environment they were raised.
Environment on the other hand does play a role in the formation of who we are and does effect the development of our personality and intelligence. By altering the environment in which a person is raised, there can be some effect on the person's developing intelligence and personality. While this is true, the results of the twin studies cannot be ignored (Westen, 2002). These studies show that our genetics have a stronger influence than our environment. Across a variety of traits, including IQ, personality indicators such as political conservatism, conviviality, and even religiosity, homosexuality, and neuroticism, identical twins are more similar to one another than are fraternal pairs. This indicates that genes affect these aspects of personality. Gene - mapping studies (Crawford& salmon, 2004) have identified individual genes associated with high IQ. There is strong evidence for the effects of nurture, for example, the fact that IQs all over the world have increased as much as 20 points over 30 years.
No matter where human beings are raised, it cannot completely change the genes that they are born with. These studies have produced substantive evidence of heritability. What varies from study to study is the quantity that can be attributed to heritability. Indication suggests that family environmental factors may have an effect upon childhood IQ, accounting for up to a quarter of the variance. On the other hand, by late adolescence this relationship disappears, such that adoptive siblings are no more similar in IQ than strangers are (Westen, 2002).
Evidence in Favor of Nurture
John Watson in 1924 attempted to challenge nature beliefs by asserting that if given a dozen of healthy infants and his own world to nurture them, he would be able to take each infant and train them to be any type of specialist he might select-doctor, lawyer or even a thief. This became a famous quote in the heyday of behaviorism, when the child was considered a 'tabula rasa' (blank slate) onto which anything could be sculpted through environmental experience. This would be a 100% environmental view, but virtually no psychologists would accept such an extreme position today (Crawford& salmon, 2004).
Influence of the Environment on Behavior and Morality
A variety of explanations might account for this. From a biologic or developmental perspective, one might argue that pre-homosexual children are more likely to be targets for molestation. In a sociological perspective, children who have pre-homosexual experiences are most likely to experience confusion over their sexual identity and later define themselves as homosexuals. From the perspective of the moral environment, one may argue that a society with a progressively more neutral outlook of homosexual behavior will grant fewer and weaker checks on those who associate early homosexual experience with a homosexual identity (Scott 1995).
Levy, a psychologist, examines the roles played by nature and nurture in the origin of moral dispositions. He asserts that evolution gives human beings a precondition of morality. However, he states that Evolution gives us the preconditions of morality, but it is only as a result of the cultural elaboration of this raw material that we come to be moral beings. He further states that human beings are animals and can never free themselves of their biological heritage. He states that human beings have no need since it enables flexibility, rational and caring behavior which they could want and allows them to seek to become more moral beings (Carlson, 2005).
Researchers on all sides of the nature vs. nurture debate concur that the link between a gene and a behavior is not the same as cause and effect. While a gene may increase the likelihood that you will behave in a particular way, it does not make people do things (Scott, 1995). This means that we still get to choose who we will be, when we grow up. Social scientists gradually understand the extent of the interactions that take place between nature and nurture. The presence of genes does not by solely ensure that a particular attribute will be evident. Genes require the suitable environments for natural tendencies to be fully articulated. These "proper environments" consist not only of natural environs but also of individuals' social and symbolic setting (Westen 2002). But even for intermediary heritabilities, a trait is always shaped by both genetic dispositions and the environments in which people develop, merely with greater and lesser plasticities associated with these heritability measures. All in all nature relies on nurture and vice versa and hence both coexist together.