The inherent physiologic capacity of an animal to respond to any sufficient stimulus seems, then, the basic explanation of the fact that some individuals respond to stimuli originating in other individuals of their own sex-and it appears to indicate that every individual could so respond if the opportunity offered and one were not conditioned against making such responses. There is no need of hypothesizing peculiar hormonal factors that make certain individuals especially liable to engage in homosexual activity, and we know of no data which prove the existence of hormonal factors (p. 758). There are no sufficient data to show that specific hereditary factors are involved. Theories of childhood attachments to one or the other parent, theories of fixation at some infantile level of sexual development, interpretations of homosexuality as neurotic or psychopathic behavior or moral degeneracy, and other philosophic interpretations are not supported by scientific research, and are contrary to the specific data on our series of female and male histories.