Excerpt: The amygdala plays an important role in helping the brain make sense of social cues. For hamsters, it picks up signals transmitted by smell through pheromones; in humans, the amygdala evaluates facial expressions and body language.
My comment: In all mammals with an amygdala it is the microRNA/messenger RNA balance that makes sense of social cues, which in humans are indirectly associated with evaluations of facial expressions and body language. For an accurate representation of how this occurs in humans see: MicroRNA-182 Regulates Amygdala-Dependent Memory Formation.
For an earlier translation of my model into the cause and effect relationships it details see: Gay, Straight, and the Reason Why: The Science of Sexual Orientation
P. 210: “This model is attractive in that it solves the “binding problem” of sexual attraction. By that I mean the problem of why all the different features of men or women (visual appearance and feel of face, body, and genitals; voice quality, smell; personality and behavior, etc.) attract people as a more or less coherent package representing one sex, rather than as an arbitrary collage of male and female characteristics. If all these characteristics come to be attractive because they were experienced in association with a male- or female-specific pheromone, then they will naturally go together even in the absence of complex genetically coded instructions.”