Implications for the teaching/learning process: revisiting nature vs nurture

Genotypes, phenotypes and development. In any examination of the nature vs. nurture issue, it is important to review a little information about the transfer of genetic material from the parents to the child. Berndt has provided a general overview of how the genotype and phenotype system works.(4) The genotype describes the genetic makeup of the child. All the observable characteristics of the child are known as the child's phenotype. It is critical to the discussion that follows to appreciate that a child's phenotype does not precisely correspond to her/his genotype for two reasons. First, the phenotype does not express all the genetic information in a particular child's DNA. Some genes may cancel or prevent the expression of other genes. Second, the phenotype of the child is determined jointly by her/his genes and by her/his experiences. In effect, the phenotype is a product of both genetic heredity and environment. However, the genotypes and phenotypes of all individuals are always related. This concept of relatedness is important to the present discussion, as is another well-documented concept, that of dominance. For the purposes of the current discussion, what you see in an individual is not all there is to know about the person genetically. However, there is a relationship between what is seen on the surface and the genetic code of the individual, which can be influenced by environment. The genetic code and intelligence. Hay argued that a polygenic model is useful in understanding the heritability of intelligence.(5) This model assumes that intelligence is the result of the combined action of many genes rather than a single gene. These genes program the physiological mechanisms that control intellectual growth, how an individual responds to various stimuli, and the predisposition to learn certain things more easily. However, Hay goes on to state that the same genotype can manifest itself in different ways at different ages with the ultimate expression of the genotype depending on a variety of complex factors. Rodgers, Rowe and May argued that the best estimate of the impact of genetic variation accounts for approximately 50% of the individual differences that exist in intelligence test scores, with the remaining 50% attributable to non-genetic factors.(6) Simonoff, Bolton and Rutter concluded that even with single gene and chromosomal conditions that affect mental ability, there exists a wide range of intellectual capacity, and it becomes necessary to