The observations of men in all ages have established the fact that in general "like produces like," and that, in spite of many exceptions, children are in their main characteristics like their parents. And yet offspring are never exactly like their parents, and this has led to the saying that "like does not produce like but only somewhat like." What is meant is that there are general resemblances but particular differences between parents and offspring...Heredity was, as Balzac sai...

One of the greatest results of the doctrine of organic evolution has been the determination of man's place in nature. For many centuries it has been known that in bodily structures man is an animal—that he is born, nourished and developed, that he matures, reproduces and dies just as does the humblest animal or plant...One of the greatest and most far-reaching themes which has ever occupied the minds of men is the problem of development...The fact of development is everywhe...

Heredity is today the central problem of biology.Heredity originally meant heirship, or the transmission of property from parents to children, and in the field of biology it has been defined erroneously as "the transmission of qualities or characteristics, mental or physical, from parents to offspring". The colloquial meaning of the word has led to much confusion in biology, for it carries with it the idea of the transmission from one generation to the next of ownership in property...