A lot of the search for a gay gene seems trapped in an outdated understanding of sexuality as a binary proposition: "you're either A or B." How do you even begin to contemplate a study on sexuality once you understand it as highly varied and fluid? Same with gender. They're bimodal distributions at best . You can't just crop off the confounding valleys and call what you do with them good science.
My understanding is that most psychological traits are now thought of as polygenic, so a statement like “there is no gay gene” is really misleading, because genetics simply doesn’t work that way.