Abstract
In this article I distinguish two main hypotheses within the endocrine paradigm for explaining the etiology of human male homosexual orientation: the postnatal and the prenatal hormone hypotheses. Using Imre Lakatos' influential methodology of scientific research programs (MSRP) as a framework for analysis, I show that although the former has been refuted by observational evidence and abandoned by most investigators, the latter continues to attract the attention of some endocrinologists as a plausible explanation of sexual preference. I further show that some of the studies purporting to support these hypotheses suffer from conceptual and methodological flaws. I conclude by saying that given these flaws, and taking into account the manner in which the proponents of this program have been responding to anomalous data, the endocrine research program does not pass Lakatos' criteria of empirical success and consequently we cannot confidently say that hormones determine homosexual orientation