I’m an openly gay man and have defined myself as such since I started to define anything at all.
Though it makes sense that there is an evolutionary, let’s-propagate component to the development of amatory aesthetics, it may only be the foundation of something very complex. Don’t forget that, even dealing only with evolutionary stuff, it’s not as if Ma Nature says “I’m gonna use lust for this purpose, hunger for that.” There may be branching-points in biohistory in which it was adaptively advantageous for an organism to do exactly the opposite of what we, with our limited information, might expect. Be VERY cautious about taking reductionist-type theories very literally.
There are a few statistical tendencies, verified by some number of experimental studies, that suggest a significant amount of cross-cultural commonality in the response to the appearance of another human. As I recall, the most important is degree of symmetry of the features. Below that, “gender cues” that are self-consistent–if it looks like (what you think of as) a female, it ought to have a female voice, a female gait, etc. Likewise, wide-hipped, narrow-shouldered men (compared to women) are viewed as at least mildly discomfitting.
Too much variance from the (statistical) norm in any area–height, weight, even, yes, penile or mammary proportions–is cross-culturally viewed as a disadvantage.
(These things are tendencies, remember, not absolute universals.)
But all of the above leaves about 95% to be customized to taste; and that’s the mysterious part.
I can only note that I found certain kinds of “looks” preferable even at, say, five years old; and those preferences have not radically changed.
It seems to me that the “typical” gay man has an aesthetic no different from the “typical” heterosexual woman with regard to identifying a lust-object. It is when we get beyond the immediate visceral responses that some differences begin to emerge, IMHO.