I personally agree on the matter of other contributing factors. Genetic predilection for certain behaviors quite often ultimately means squat in the face of human culture.
Physiology is another matter. Disease resistance or susceptibility, dietary tolerances or intolerances, et cetera - these are the sorts of things where your genes really matter. But when it comes to the mind? To learned behaviors? Genes are a drop in the bucket.
I don't buy the "born this way" argument. It strikes me as absurdly simplistic. History is full of ready examples of how wrongheaded it is, where individuals of a certain genetic background enter into the culture of a group of people from a separate genetic background at a very early age and adopt it as their "native" culture. Behaviors and thoughts completely alien to their people and ancestors become so deeply ingrained as to be utterly "natural".
Look at the Turkish Empire and its countless Christian slaves, many of whom were taken as infants and had no knowledge or memory of their original families or European life. In their minds they were Turks and Muslims, despite coming from Christian European stock. Their behaviors, their beliefs, their feelings and their personalities were the product of their upbringings - not their genetics.
How can anyone attribute sexual attraction to genetics any more than they can attribute religious belief, or political affiliation, or philosophical creed, or linguistic preference? With values of beauty and sexuality being so amazingly twisted up in tradition and cultural imposition, how can they possibly expect their analyses to be at all accurate or significant?
The only way to get a pure reading would be to study humans raised in the absence of extant cultures - removing the influence of human conditioning and examining the natural, spontaneous behaviors outside of cultural paradigms and societal expectations.