A gene provides the code for generally one (there are exceptions) protein. There are some appearances, conditions or illnesses which are the product of the presence or absence of a a particular protein. I think Albinism and Sicle Cell Anemia are examples of such conditions/illnesses. I cannot imagine that any behavior could be explained by the presence or absence of a single protein. I suspect that almost all behavioral traits are the product of many genes, nature, and one’s free will. I’ll take a wild guess that so many genes are involved that it is not currently practical to collect the data (study enough people) or have the computational power to map human behaviors to a particular set of genes. So yes, I don’t believe there is a single ‘homosexual gene’ but I believe there is a strong genetic component. I know I couldn’t suddenly ‘decide’ that I was no longer heterosexual.
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Your personal experience or belief does not rise to the level of proof.