TOP > About Child Science > Kodomogaku Kotohazime (1998-2000) > Biological Foundations of Children's Heterogeneity


Biological Foundations of Children's Heterogeneity

Children are heterogeneous. Globally, each child differs in ethnicity, race and nationality, while even children living within the same country (i.e. Japan), differ in terms of age, gender, home environment and schooling. Even children born into the same family with the same parents will differ on their physical appearance and ability, intelligence, emotions and will. This is what I refer to as the heterogeneity of children.

Children's heterogeneity can be explained by dividing it into two parts, (1) biological and (2) social. Biologically, children can differ in race, blood type, body type which can all be traced back to one's genes. On the other hand, social heterogeneity can be based on the family environment, school, community and the country in which a child comes into contact. These prescribe the socially learned behavior patterns of the child which are acquired through socialization in the home and school.

I would now like to speak about the basic biology which determines the genetic heterogeneity of children (humans). Specifically, I would like to elaborate on the genetic mechanism of how, with the same parents, even siblings can turn out to be so different.

To begin with, the spermatozoon from the father joins the mother's ovum to fertilize it, which is followed by cell division. The egg then grows into an embryo and then into a fetus eventually becoming introduced into the world leaving the mother's womb. As you see, this reproductive cell formation is what becomes the key to a child's heterogeneity.

Each cell of the body contains the 46 chromosomes, each chromosome is packed with millions of genes that will determine a child's every characteristic. From these body cell, the sperm or ova is produced. Although the formation of sperm has been well documented and researched, the formation of the egg is still being researched. When the reproductive cell is to be formed, the chromosomes need to be halved in number, that is, 23 chromosomes. This process is known as meiosis. During the meiosis random assignment of the material or paternal chromosome of the body cell will occurred, as well as the X,Y chromosomes which eventually determines the sex of the child.

The possible combination of chromosome that are passed down from one's parents and then from his or her parents can total about 8,400,000 (223), which is calculated simply by the random assignment. In addition, the chromosomes undergo a process of "cutting and pasting" as exchanging of parts of chromosome called chiasma.

Thus, the possible number of chromosome combinations produced by random assignment of material chromosome and exchanged chiasma, is extremely numerous, almost beyond explanation. Thus, the life of one child given from his/her parents is something very unique and special, genetically speaking. Except for the case of identical twins, in the long history of mankind, there has not been an example of two human beings with the same genetic composition being naturally born, and I certainly don't foresee it in the future.

I am sure that anybody watching children play together, fight together, comfort each other, will be impressed by the uniqueness of each child, as well as their heterogeneity. This is the result of the remarkable biological basis of human beings. It is more important to know that their heterogeneity themselves produce power to support our society as well as to produce culture and civilization.
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