Heredity And Environment B.Ed Notes | Laws of Heredity

Heredity And Environment B.Ed Notes

Meaning of Heredity

Heredity is considered as "the sum total of inborn individual traits".

Biologically it has been defined as "the sum total of the traits potentially present in the fertilized ovum.”

It has been seen that a cat gives birth to a kitten, a dog to a puppy and a human being to a human being. It is on account of this factor that we say that the class of dogs will give birth to puppies, or that like begets like'. Still, there we find much variation between different dogs or cats or human beings even if they are born of the same parents.

The effects of hereditary factors

The effect of hereditary factors on behaviour has been condensed by Anne Anastasi, a well known American psychologist:

1. Hereditary defects may exist which makes normal development impossible, such as in the case of inherited metabolic disorders.

2. A hereditary defect may affect development of making it difficult or impossible for the individual to interact fully with the environment. Such an example would be hereditary deafness or the sex-linked characteristic of haemophilia.

3. Hereditary defects may make the individual more subject to particular types of physical disorders. This appears to be true in the case of hereditary feeble-mindedness in which respiratory infection is very frequent.

4. Hereditary factors determine some of the physical characteristics of the individual, such as skin pigmentation, sex and stature.

Hereditary or genetic conditions set the limits but the accompanying environmental factors may modify their effects.

LAWS OF HEREDITY

1. Like begets Like : This principle states that the children have a tendency to be like their parents-like father, like son. The children of bright guardian tend to be bright and those of dull, tend to be dull. In the same way, handsome parents tend to have handsome children and ugly parents tend to have ugly ones.

But this law is not universally true. It has exceptions. Sometimes, we see that white parents have black children or bright parents have less bright children. Such occurrences can be explained by the second law of inheritance, known as Law of variation'.

2. Variation : The children are not exactly like their parents. They have differences of features, etc. The law of variation explains the causes of these differences in the children of the same family. It is due to the fact the germ-cells of the parents have genes which unite in various ways; and each combination produces a different quality of offspring. That is, there will be as many variations as there are possible combinations of genes. We sometimes find that the same parents have children who are very different from one another. It is because of the different combinations of genes, the different combinations will give birth to different types of children, e.g., one combination would produce a white child, the other a black one.

But, we must remember that though the children of the same family are different in intellect, etc. 

3. Regression : According to Sorenson, "The tendency for the children of very bright parents to be less bright than their parents and a comparable tendency for the children of very inferior parents to be less inferior, is called regression.”

The children of brilliant parents will tend to be of average intelligence. It is so, because every trait has a regressive tendency towards the average. We do not mean to suggest that regression always occurs; but the existence of such a tendency cannot be denied

Often it so happens that very talented parents do not give birth to equally talented children. The reasons for regression may be cited as follows:

(i) The union of the best traits of the father with the best traits of the mother produces talented child. Therefore, a talented father or mother must be the child of the best combination of the determiners in the germ-cells of his or her guardians. But such gifted parents may carry on the determiners of genes which are average. When they will produce a child, there are many chances that their average traits combine and a child of average calibre may be the result. It is usual that the talented children carry on the determiners which are average or inferior to the combination which had produced them.

(ii) If a gifted parent mates with a person who is less gifted and carries inferior determiners, the resulting offspring may be of an inferior calibre. The reason is that in such a case that fine combination, which produced the gifted parents, has not taken place.

Likewise, the offspring of idiotic parents would be better, if the germ-cells of the parents are better than the combination from which they have been developed

These are laws of heredity which help in understanding human characteristics and qualities.

Meaning of Environment 

In the ordinary sense of the term, environment means all that is found around the individual. 

Douglas & Holland, in their book, Educational Psychology, define the term,

"Environment" as "a word which describes, in the aggregate, all of the extrinsic (external) forces, influences and conditions, which affect the life, nature, behaviour and the growth, development and maturation of living organisms."

In fact, environment constitutes all which is found in the child's mental, moral and spiritual universe.

Heredity and environment are of equal Importance

It may be noted here that studies pertaining to the relative importance of heredity and environment are inconclusive and it can never be said that heredity is more important than environment or environment is more important than heredity.

According to Anastasi, "Both heredity and environment contribute to all behaviour traits, and that the extent of their respective contribution cannot be specified for any trait."

From the point of child development, it is generally accepted that, "Inherent characteristics of the organism which will unfold under appropriate conditions of life experience, buit which may also be suppressed or distorted if environmental factors are adverse to their realisation"

In the words of Woodworth & Marquis, "The size of the difference between two individuals always depend on both factors.” (i.e., heredity and environment). Further, they point out that, "Improving the environment for all alike would not tend to make individuals equal." In other words, both heredity and environment are essential and it is not possible to improve any one's heredity.

The example of seed and soil illustrates the relative importance of heredity and environment. If we sow good seeds in a poor soil, the crop will also be poor in spite of good seeds. It may be noted here that seed represents heredity and the soil environment.

If the seed is good and the soil is also good, only then we can have good crop. Thus, it is quite evident that 'both heredity and environment may occupy a place of equal importance.