Heredity refers to the biological process of transmitting traits from parents to offspring. It comes about through the union of male and female cells, and it manifests itself in such things as eye color, body shape, mental capacity, and numerous other physical and psychological tendencies which characterize the newborn child. Heredity sets the stage, so to speak; provides the "stuff " out of which human behavior emerges; establishes the potentials. Heredity plays its last hand at the time of conception, and though the product may be modified after that, environment can never completely change what nature has done.
The physical environment consists of various material elements and energies that at all times surround the human organism, influencing both development and behavior. Before birth it is made up of chemicals, temperatures, and other conditions within the mother. It is affected by such things as diet and exercise; and it, in turn, affects the growth rates, survival chances, and general health conditions of the child not yet born. After birth it consists of the many geographic factors--temperature, rainfall, sunshine, wind, soil, mineral resources, elevation, topography, and the like. During the prenatal stage this physical environment is the only one operating. In the postnatal, however, there are competitive influences along with it --the social and the cultural. Culture, particularly in the Western world, has developed nearly far enough to supersede geography in influence. To some extent man has learned how to control temperature, remove mountains, and in other ways harness the forces of nature to his advantage. Modern man is not nearly so dependent upon the elements as were his ancestors. Yet, neither is he independent of them. Though the physical is perhaps the least important of man's postnatal environments today, it is nevertheless there and it has influence. To give but one example, soil compositions in the Great Basin area of the West result in iodine deficiencies in diets built from foods grown there. This condition, in turn, produces a higher rate of goiter in that area, with some ill health and personality tensions as end results.
The social environment comes from the presence of other human beings and one's interaction with them. This is sometimes referred to as the "group situation." It starts with birth and continues normally throughout the lifetime of the individual. "Man is a social animal" said Aristotle many years ago. By this he meant that society, or the interaction of peoples in groups, has a great deal to do with man's behavior. There have been rare instances of men's being deprived of this social or group environment and/or remaining undeveloped or "wild" because of it. Such individuals, those growing up or living for long periods of time without or with little human association, are called feral men. 2 They are odd because they have not had an opportunity to become socialized through normal contact with others. No personality can develop normally and completely in isolation. Everyone is influenced by, and also influences, those around him.
The cultural environment is made up of the multitude of man-made objects, customs, understandings, and skills that one is born to accept. Culture is sometimes defined as man's "social inheritance," for just as individuals are different, depending upon the kind of biological inheritance that is theirs, so they are also different, depending upon the kind of society into which they are born.
Someone born to live in the heart of New York City, for example, would have a far different social heritage, and therefore a different personality, from another on the upper reaches of the Amazon. Culture, though not the same as society, is one of society's products. It consists of all that is created by man in interaction, deposited or retained by society, and passed down from generation to generation.
Thus it is that man is the product of a number of forces, all interrelated. Biology starts him off, lays down the raw materials out of which he can grow, establishes tendencies, sets limits. The physical environment, operating both before and after birth, influences his general health and, in some cases, also sets limits upon his development and activity. Starting soon after birth, both the social and the cultural environments come into strong play, the first by an interstimulation and interresponse of persons in contact with one another, and the second through an exposure to the traditional ways of thinking and acting that the group has built up. Personality is the outgrowth of them all.
It isn't really a question of nature versus nurture, as some would have it, but nature and nurture, operating jointly and with interactional effects. Heredity makes the start by providing materials out of which personality is to be built. But it is to the environments, mainly those social and cultural, that we must turn if we would understand the dynamics of personal action and the variability in directions of development. The age-old argument on the relative importance of heredity versus environment is fruitless, for both are absolutely essential and it is only through the interaction of one with the other that personality comes about. Science has not progressed far enough to give exact proportions for the various components of human behavior, nor is it likely that it will ever be able to do this. The important thing is to know what these components are, how they operate, and that they function in unison.