How Homosexual Orientation may Form


(Copyright 2006, James Michael Howard, Fayetteville, Arkansas, U.S.A.)



I define sexuality as activation of neuroanatomic, physiological circuits in the brain that stimulate sexual activity in response to environmental cues and activity from pleasure circuits in the brain.  (I think hunger, etc., work the same way.)  I think sexual orientation is affected by growth and development of neuronal nuclei in the brain.  These centers may be affected by molecules from the environment (smells or pheromones).  If one has smaller sized nuclei, the amount of molecules required to activate the nuclei may be less.  That is, fewer cells, or less growth of cells, in a group may be activated by fewer molecules to “send” a signal for behavior.  I think growth and development of some of these centers is similar in women and homosexual men; I think research has demonstrated similarity in size.  Therefore, these centers may be activated more rapidly than larger centers because of less surface size and therefore, the receptor density to nuclei size is increased.  So, as an individual grows and develops and is around adults and other children, girls and homosexual boys will be activated sooner by lower levels of molecular signals (scents or pheromones).  In this case, the smell of men may be stronger and affect stimulation of these areas more rapidly, therefore, orienting these individuals towards responses to males.  That is, an activating smell may affect smaller nuclei more rapidly and establish a sexual link with the main activator, men.  Larger nuclei may require increased activation and these may be activated later because of increased activation by arrival of young women to puberty.  This may also explain the strong bonds between males that are later supplanted by women.


There may be support for my hypothesis.  A derivative of both progesterone and testosterone, 4,16-androstadien-3-one (AND), has been studied as a “pheromone” in male and female homosexuality. AND activates the brain of heterosexual women and homosexual men similarly (first reference below) but not homosexual women (second reference below).  Homosexual women were activated by “the estrogen-like steroid estra-1,3,5(10),16-tetraen-3-ol (EST)” which is also thought to be a human pheromone somewhat similarly to heterosexual men (second reference below).  This differential in activation may be due to increased activation of smaller nuclei in women and homosexual men.  Of interest here is that both men and women will produce AND which will stimulate both hetero- and homosexual orientation depending upon growth and development of the affected child, in utero.  So, a child with heterosexual growth and development of their brain nuclei will develop according to their own program and not be affected by either male or female homosexual parents.


At puberty, testosterone, in men and women, increases activation of these circuits.



“In contrast to heterosexual men, and in congruence with heterosexual women, homosexual men displayed hypothalamic activation in response to AND. Maximal activation was observed in the medial preoptic area/anterior hypothalamus, which, according to animal studies, is highly involved in sexual behavior.” (Proc Natl Acad Sci U S A 2005; 102: 7356-61)


“In contrast to heterosexual women, lesbian women processed AND stimuli by the olfactory networks and not the anterior hypothalamus. Furthermore, when smelling EST, they partly shared activation of the anterior hypothalamus with heterosexual men.” (Proc Natl Acad Sci U S A 2006; 103: 8269-74).