The process by which genes and environment operate together to influence development

This essay will seek to examine the theories of genetic determination, genetic programs, and gene-environment interaction before looking at the transactional model of development as the most accurate framework to examine both physical and psychological development respectively. ‘Genes are not like engineering blueprints; they are more like recipes in a cookbook. They tell us what ingredients to use, in what quantities, and in what order – but they do not provide a complete accurate plan of the final result. (Stewart, 1998)

Thus, this essay will seek to show that any theory of child development must take account of gene-environment interaction if it is to offer a holistic picture of child development. The notion of development as a process of genetic determination has dominated psychological theories throughout the ages, in particular theories that have developed from a nativist perspective. From this viewpoint genetics determines the holistic picture of development from physical to psychological. Development is predetermined and subsequently our potential to develop characteristics is fundamentally fixed and therefore limited.

Maria Montessori advocated this nativist theory and developed an educational system whereby children could develop without the restrictive confines of the conventional educational regime. (Richardson, 1994, p. 63) Kerbs and Davies (1981, p. 12) argued that ‘in a sense all behaviour must be coded for by genes; reduced to its simplest form behaviour is nothing more than a series of nervous impulses and muscle contractions and the protein structure of nerve and muscle is coded for by genetic instruction. However, one could argue that while genetic determination adequately explains physical development it fails to sufficiently account for psychological development. For example, our intelligence rarely reaches a definite endpoint, as it is constantly changing throughout our lives, therefore, negating the notion of a ‘fixed potential. ‘ In order to validate its theory, genetic determination needs the environment to remain constant over hundreds of years so that information can become part of our genetic make-up through the process of natural selection.

Bowlby’s theory of attachment is a prime example of this process as persistent predator threats continued across many generations. (Richardson, 1994, p. 64) As a result, young children developed an instinctive attachment to their mothers. However, our environment is in a constant state of flux and one could even argue that it changes within generations, primarily through technological advances. Therefore, genetically determined development is not an efficient way of ensuring adaptation in highly changeable environments. Plotkin and Odling-Smee, 1979) Consequently, more adaptable systems are needed and the theory of developmental plasticity emerged to account for changes in the course of development.

Piaget (1980) cited water snails to support this theory of developmental plasticity. Water snails developing in pond habitats had elongated shells, whereas the same species developing in more turbulent lake conditions had more compact shells, better able to stand up to turbulence. (Richardson, 1994, p. 5) Developmental plasticity suggests that genes have ‘self-organising’ properties and can therefore direct their own development to some extent as opposed to a rigid maturation. From a constructivist perspective one could note the genes interacting with the environment in the process of development.

Consequently, there is need for an epigenetic view of development, whereby information over and above that contained in the genes is central to development. Development is no longer a passive act as in behaviourism and nativism but rather it becomes an active process by adapting to the outside world, as in social constructivism. Richardson, 1994, p. 66) We cannot solely look at child development from a genetic perspective and equally we cannot look at it in isolation from an environmental viewpoint. We need to amalgamate both perspectives in order to obtain a clearer picture of child development. Our changing environment forces genetic changes, a fact, elucidated by the colour adjusting mechanism of the chameleon and the sex-reversal mechanism of the coral reef fish. (Richardson, 1994, p. 68) However, humans have to cope with more abstract and complex changes.

Newell (1990) accounts for these changes with a term called ‘efflorescence of adaptation. ‘ Newell stated that humans go around simply creating opportunities of all kinds to build different response functions. He believed humans invent new adaptations faster than they can be recorded. (Richardson, 1994, p. 84) Evolution has developed a further level of adaptability through individual experiences whereby we create ‘internal models. ‘ This knowledge and behaviour is transmitted from parent to child, without direct prior experience of the problems themselves.

The child acquires models of social interaction, sometimes in the form of tangible instruments. The Soviet psychologist Leontiev illustrated this with the example of a baby feeding with a spoon. ‘At first they handle the spoon as they would any object. But this handling is reorganised by adult intervention to conform to a more specific social model. ‘ (Richardson, 1994, p. 76) This is an obvious example of external forces (environment) moulding the psychological behaviour of the child.

Therefore, if we are to understand the development of psychological characteristics we must approach it from an epigenetic perspective. Gene-environment interactions are intricately woven together and distinguishing the effects of each in isolation is a mammoth task. This difficulty can be overcome in the study of animals as we can produce pure strains with particular genetic constitutions through selective breeding and control the influences of both genes and environment in properly designed experiments. (Richardson, 1994, p. 16) This is not possible in humans and we are therefore forced to draw on observations and theoretical models.

Arnold Gesell carried out such observations of the early behavioural development of children. He found that we go through stages of development (maturation) the effects of which are contrasted with those of the environment. He stated that environmental factors are certainly vital, in that they support growth, but they play no direct role in the sequential unfolding of structures and action patterns. (Richardson, 1994, p. 58) For Gesell, the child clearly needs its social environment to realise his/her potential. What Gesell described became known as a ‘genetic program’ for development. Genetic programs are an elaboration of the general principle of genetic determination and an example of rationalist theory. (Richardson, 1994, p. 218) This theory sees environmental input as necessary only in the same way as food is necessary for growth; it has little influence on the end result. One could certainly argue against the view that the environment has no direct role in development.

We only have to look to a prior example of a child feeding with a spoon to see the direct influence of the environment on the development of the child. If the adult did not show the child how to use the spoon what would the outcome be? There is clear evidence of genetic programming for physiological characteristics, for example, the eye, primary and secondary sexual characteristics, and the rooting reflex in new-born infants. (Richardson, 1994, p. 219) However, evidence to support the psychological development of genetic programming is once again hard to find and support is mainly in inference and argument.

Chomsky supports genetic programming arguing ‘Our biological endowment determines both the scope and limits of physical growth … when we turn to the mind and its products the situation is not qualitatively different. ‘ (Richardson, 1994, p. 219) He cannot imagine any other explanation for the development of psychological characteristics, such an argument is very weak and without any real foundation. It is thought that since the infant has had little world experience, any apparently well-structured abilities must have been formed by a genetic program prior to birth. Richardson, 1994, p. 220) Even children born deaf and blind have the same expressive movements (smiling and crying) as other children, which would suggest that they are innately specified. (Richardson, 1994, p. 220)

There are many criticisms surrounding genetic programs among them the lack of hard evidence from controlled experiments. In addition, genetic programming fails to account for Newell’s ‘efflorescence of adaptations’. (Richardson, 1994, p. 221) Alternatives to the genetic program are a relaxed genetic program, or associationist and constructivist alternatives. Richardson, 1994, p. 221) Quite different genes in different individuals may produce identical outcomes in the characteristic; or the same genes may produce different outcomes (for example the water snails). These epigenetic effects may be accentuated or diminished in different environments. The situation becomes even less predictable when we move to ‘self-organising’ characteristics in which the ‘outcome’ is a kind of ‘steady state’ in a dynamic system, such as development of new skills, rather than a fixed function such as a reflex. (Richardson, 1994, p. 30)

Theodore Wachs (1992) has carried out research on environment and development, identifying environmental factors such as region of development, social class, and parental level of education. The developmental outcomes included school attainment, IQ, social adjustment, and personality. (Richardson, 1994, pp. 232/3) His research found that variations in environmental experiences appear to be associated with variation in child development. This was further highlighted by the Macaque Monkey study, where three different strains of monkeys were reared in isolation.

The result was that different strains exhibited different patterns of deficiency in behaviour. (Richardson, 1994, p. 238) Therefore, one could deduce that to examine the development of psychological characteristics we need to adopt a more flexible model of development. The transactional model developed by Sameroff (1991) recognises that the child is not merely passive in their development, but rather plays an active role in that development. (Richardson, 1994, p. 239) For example, the perceived temperament of a baby can influence the parents’ attentiveness to their child.

If the child was to be unsettled and crying continuously the parent could become less responsive to the child, which in turn would reduce the amount of oral interaction with the child, which would have a further impact on the child’s early language acquisition. Buss and Plomin accept the nativist view of Eysenck that personality is formed by the expression of biologically determined tendencies to behave and react in certain ways, whereas Rutter sees personality as being a product both of the biological and social influences (social constructivist). (Stevenson and Oates, 1994, p. 67)

One would have to agree with this social constructivist view as it allows the environment to interact with genes and to contribute to the development of psychological characteristics. Up to the time of birth the role of genes is straightforward, but they then set an entirely different developmental sequence in train. The first of these starts at the very moment of birth when incorporation of the sex distinction into a complex social system commences. (Richardson, 1994, p. 240) It is our genes that make us fe/male but it is our environment that develops our complex gender identity.

In conclusion, certain aspects of child development are best understood within an epigenetic framework namely physical characteristics e. g. growth of limbs, eye and hair colour etc. However, in order to gain a greater insight into the development of psychological characteristics we need to adopt a more multifaceted approach to development. No theory of child development can be complete without looking at gene-environment effects. The complex interaction that occurs between mother and child requires the use of a transactional model if we are to fully understand the holistic framework for child development.