So far as we know, each coming generation will inherit only qualities that the parents inherited from their parents. It is a well-known principle of biology that changes in the bodies of human beings during their lifetime (dating from the fertilized egg that produces the individual) are never in any noticeable degree inherited by descendants. In short, acquired characteristics of the body tissues do not influence the germ plasm, the living matter concerned with heredity and reproduction, but the germ plasm that determines what the next generation will inherit is fixed at birth. Thus tuberculosis, alcoholism, gonorrhea, and syphilis may be acquired during the life of an individual, but do not become fixed in the germ plasm. If the infants show effects of any of these diseases, it is not because of true heredity but because they were infected or influenced before birth. Rarely does this happen to children of a tuberculous mother, but often to those of a syphilitic mother. In a gonorrheal ophthalmia neonatorum (specific inflammation of infants' eyes) it is a case of infection during birth.
Sex-hygiene and eugenics parallel.
Thus, it appears that sex-hygiene either personal or social (concerned with venereal diseases) is not a part of eugenics. It is, however, a phase of euthenics, which deals with the environmental factors that affect the individual life. It is clear, then, that sex-hygiene (in the strict medical sense) and eugenics are parallel and not conflicting. Eugenics aims to select better parents who will transmit their own qualities genetically. Sex-hygiene in its personal and social aspects will make healthier parents able to give their offspring a healthier start in life, especially because the offspring is free from the prenatal effects of disease.
The teaching of heredity and eugenics is intended to develop a sense of individual responsibility for the transmission of one's good or bad inherited qualities to offspring. The teaching of sex-hygiene, either personal or social, looks towards improving personal health and preventing infection and injurious influence on the unborn next generation. Obviously, we need both sex-hygiene and eugenics as part of the larger sex-instruction.
§ 14. Summary of Lectures on Sex Problems
Problems of health, attitude, and morals.
We have made a general survey of the problems that offer reasons for sex-instruction. We have noted that some of the problems are concerned with health and, hence, lie within the scope of sex-hygiene in the strict sense of that term; but some of them have only the remotest relation to health and hygiene. On the contrary, they relate to the ethical, social, and æsthetic attitude of individuals towards sex and reproduction. Obviously, these touch problems not of sex health, but of sex morality. In their educational importance I believe them as great, perhaps even greater, than those of sex-hygiene. In fact, I have come to believe that many individuals can best solve all their own sexual problems on the basis of moral and æsthetic attitude.
Many-sided instruction needed.
Considering, as we have done, the sex problems in their many aspects, we are forced to the conclusion that sex-education will prove adequate only when it combines instruction from the several points of view. It must be much more than the sex-hygiene with which the sex-instruction movement started. We need sexual knowledge that will conserve health, that will develop social and ethical and eugenic responsibility for sexual actions, that will lead to increased happiness as well as to improved health, and that will give a nobler and purer view of life's possibilities. In all these lines in which sex influences human life profoundly, sex-education holds out the hope of help towards a better life for all who receive and apply its lessons.