Heredity means continuity of features from one generation to another. Eggs laid by a sparrow hatch into sparrows, but never into any other bird. A dog reproduces to give birth to pups only. This is the essence of heredity. Hereditary information is present in the fertilized egg of zygote. The zygote develops into an organism of a particular type only. Asexual reproduction individuals belonging to a give line of descent. While in sexual reproduction, both similarity and variation are clearly observed even among the off springs. Thus Heredity is the resemblances among individuals related by descent or the transmission of traits from parents to the off springs.
The concept of Heredity is not new. Selective breeding of horses and cattle used to be done during the ancient civilization of Babylon and Assyria. Ancient Chinese writings mention about creating better varieties of paddy. Charkara(100 BC) , the ancient Indian medical practitioner is evident from the fact that he knew the factors that determine the sex of a child. But the scientific principles, which govern patterns of inheritance, were unknown till the experiments and findings of Gregor Johann Mendel. Thats why he is called as the father of genetics. Mendel factors, the carriers of hereditary information, are what we know today as “genes”, a term coined by Johanssen in 1909.
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