Are we the way we are because of the situations which we come across in our life or the actions we choose in our life are already hard wired by our DNA? This is a perennial question and it is difficult to choose an answer. Several experiments have been conducted by the scientists on this question and answer is ‘both’ ie, we are the product of both the nature (genetic background) and nurture (environmental factors).
There are many factors that influence the development of an individual. One cannot account for each and every factor and finalise the most influencing factor in the growth and development of an individual. However, interactions of heredity and environment begin to shape the children even at the earliest moments of their life.
What is heredity?
Douglas and Holland have defined heredity as follows: “one’s heredity consists of all the structures, physical characteristics, functions or capabilities derived from parents, other ancestry or species”. The answer to the question, how does the inheritance happen is given below.
The developmental process of an individual begins at the moment of conception, when a male sex cell or sperm unites with and fertilizes a female sex cell or ovum to form a single new cell called zygote. This newly formed cell contains 23 pairs of tiny particles called chromosomes. One of each pair is transmitted by each parent. Each chromosome contains smaller substances known as a gene; and each gene is a carrier of one or more hereditary character. Thus, the genes determine the inherited potentialities of the child.
A few hours after conception, the zygote begins to divide and subdivide into new cells until billions of them have been formed. These cells eventually differentiate into specialised parts of the body such as the brain, sensory organs and muscles.
What is inherited?
Strictly speaking the child does not inherit the traits of the parents; it inherits a set of genes, which determines the child’s inherited potentiality. ‘Genes’ refers to units of inherited information that consist of DNA and are located on chromosomes and can exist in alternative forms called alleles. Children inherit the traits of the forefathers besides those of immediate parents and they are transmitted to the off springs through these genes. Therefore, it is possible that a child may possess traits of one or more of the ancestors even though they may not be visible in either of the parents. Experiments in psychology show that heredity contributes to physical, mental, emotional and social development of an individual.
What is environment?
Regarding environment, American Heritage Dictionary of the English language fourth edition states: “Environment is the totality of circumstances surrounding an organism or group of organisms especially the complex of social and cultural conditions affecting the nature of an individual or community”.
Physical characteristics
It is found that the child inherits physical characteristics such as height, the size of bones, the colour and texture of hair, the colour of the eyes, shape of the face, nose; in short the entire physical structure.
In this context, the importance of environment for physical development needs emphasis. Studies have shown that nutrition from mother, and hence mother’s diet influences the growth of the embryonic cell. Hormones secreted by endocrine glands are discharged into the blood stream of the mother affect the subsequent development of the embryo. Similarly, infection, illness and emotional stress during gestational period, affect the human embryo although it does not disturb the genetic arrangement within the zygote.
Mental traits
Experiments have proved that child inherits psychological characteristics including intelligence and personality traits although environment also plays a significant role.
Is intelligence inherited?
Intelligence test administered to blood relations by the psychologists shows the evidence that intelligence is inherited.
Studies conducted on identical twins shows that the coefficient of correlation of identical twins is as high as .90; and in the case of cousins is as low as .25. Naturally it may be concluded that the twins have the same inheritance, and cousins do not have. But apart from inheritance, environmental conditions regarding their material facilities and manner in which the twins are brought up may influence intelligence. Psychologists measured the intelligence of twins reared together, and twins reared separately. The result shows three facts:
- The coefficients of correlation in the case of twins reared together and separately are both high.
- The coefficients of correlation in the case of twins reared together are higher than those in the case of twins reared apart.
- The coefficients of correlation in the case of twins reared apart are higher than that in the case of siblings.
The study shows that heredity is an important factor that contributes to intelligence and environmental influences are also equally important.
Another detailed study on the effect of environment on foster children shows that intelligence as shown by IQs develop better in richer and more stimulating home environment, and the longer the children are kept in which environment the greater is the increase in the IQs.
Several studies determine the influence of heredity on personality characteristics such as temperament, eclectic imagery, handwriting as an expression of personality traits, traits revealed by Rorschach records neurotic disposition etc. The results have shown that identical twins are more alike than fraternal twins. Although it is a strong point in favour of heredity, it is found that many of these studies have serious contradictions. Eysenck on the basis of his work has concluded that neuroticism is to a large extent inherited.
Emotional qualities
Emotional development is also a product of both heredity and environment, or more correctly of both maturation learning. For example, all children smile, laugh and cry at distinctive age levels irrespective of the stimuli given to them. These emotional expressions appear precisely at the same age level in all children even if they are restrained from witnessing these behaviours in other people. Again, child is not at first afraid of fire or a centipede. In fact the colourful beauty of the former and the quick movements of the latter attract the child. The child does not fear till the adults teach him to be afraid of these. Thus, the example shows the influence of heredity and the other shows significant role of both in a human development.
Social traits
Available evidences are of two kinds.
- Infants show a significant difference in social inheritance.
- Infants of the same family show different patterns of social behaviour.
Here the difference among children is due to differential status or treatment. In this context, hereditary factors listed above do not fully account for social development at any stage. But environmental factors greatly influence the behaviour of child at every stage.
Whether heredity or environment plays a decisive role in the growth and development of the individual is an age old debate that has puzzled the psychologists and educators for quite long time and it still continues. From the above discussion it is clear that heredity and environment are equally important for the growth and development of the individual. In the words of Kolesnik, “human development is the product of the interaction of man’s inherited potentialities and his environment”. The individual inherits many physical and cognitive qualities, and environment determines the form and direction in which inherited potentialities develop. Without environment, inherited qualities will lie dormant. But even the best environment cannot create certain physical and mental abilities. Thus heredity (nature) and environment (nurture) are complementary factors, and not opposing factors as considered by earlier psychologist or advocates of each. Theories of development cannot escape without considering gene environment interaction.
The facts mentioned above have great educational significance. The teacher should recognize that everyone has certain inherent potentialities, and they are the limits set by heredity beyond which one cannot progress. Therefore, the teacher should attempt to find out the innate abilities and tendencies of children which he should improve through proper materials and methods of instruction.
It is not proper to feel that every possible line of development of the individual is laid down by heredity, and no amount of effort on the teacher’s part can bear fruit. In fact, it is not possible to know exactly what children inherit individually. Besides, emotional and social development of the child – is to a large extent determined by environmental influences. Therefore, teacher should provide suitable environment by way of instruction and activities which would contribute the maximum to the development of whatever qualities which the child inherits.