The neem tree does not bear mangoes and the mango tree does not bear apples. The children of human beings resmble their parents. This is the universal truth that the offspring of all the living beings have close resemblance to their parents. Do you know why it is so?
The answer to all these questions can be had from the genetics--the science of heredity. It deals with all those factors which are responsible for the close resemblance of the offspring to their parents. Heredity is another name of the transmission of cahracteristics form the parents to their offspring. These are inhereted from parents through very minute particles called as genes.
It is a part of a cell. There are some 20,000 genes in the nucleus of every cell.Out of these,some ten thousand of them are inherited from the mother and other tem thousand from the father.All these genes are contained in 46 chromosomes in the nucleus having a diameter of 0.01mm.At the time of conception 23 chromosomes come from the fate and 23 from mother,thus,there are 23 pairs of chromosomes in every cell. The gene is the unit of heredity.
Gregor Mendal a biologist from austria, is called as the father of genetics. He conducted many experiments and formulated certain rules known as Mendal's laws. He showed through experiments that the dominating genes of parents dominate the traits of the children also. For example if the eyes of one parent is brown and those of the other is blue then the eyes of the child would be brown colour since the brown colour has the dominance over the blue. In this way genes are responsible of the close resemblance of offspring of their parents.