Debate on the relative contributions of nature and nurture to an individual’s gender patterns, sexual orientation and gender identity are reviewed as they appeared to this observer starting from the middle of the last century. Particular attention is given to the organization-activation theory in comparison to what might be called a theory of psychosexual neutrality at birth or rearing consistency theory. The organization-activation theory posits that the nervous system of a developing fetus responds to prenatal androgens so that, at a postnatal time, it will determine how sexual behavior is manifest. How organization-activation was or was not considered among different groups and under which circumstances it is considered is basically understood from the research and comments of different investigators and clinicians. The preponderance of evidence seems to indicate that the theory of organization-activation for the development of sexual behavior is certain for non-human mammals and almost certain for humans. This article also follows up on previous clinical critiques and recommendations and makes some new suggestions.
The evidence for androgen-induced organization-activation in non-human mammals is clear. The preponderance of evidence does point in that direction for humans as well but the evidence is less clear. Due to pre birth conditions the human appears to be biased towards sex appropriate patterns of behavior, sexual orientation and gender orientation. The reason for the lack of surety is simple. With animals experimentation is possible so one can modify parameters of study to get a better understanding of cause and effect relationships. This is not ethically proper for humans. For humans it takes so-called experiments of nature and different clinical situations to offer opportunities for analysis. And basically the human experiments of nature are in the areas of intersex and different trans conditions, principally transsexuality.
At these levels of clinical concern the information available is high on anecdote but low on long-term evidence. Nevertheless, direction toward treatment has to a large degree come from the theory of organization-activation. Its signiﬁcance in this regard cannot be overstated. From its inception to current times organization-activation theory has stimulated all sorts of experimental animal studies resulting in important conclusions. The organization-activation theory has also provided great insight to clinical conditions and their management. It has served us well over these past 50 years.