Although there are certainly environmental factors to sexual orientation, there have been plenty of studies that also show there is a genetic factor to sexual orientation, which means there is some kind of "gay gene" although that is an oversimplification. It is unlikely that this is a single gene - genetic personality traits tend to be multifactorial predisposition traits that involve multiple genes and require more or less environmental involvement to express depending on the individual.
Here's a simple question to people who think homosexual behavior is a choice: "When did you choose to be straight?" If the answerer is an honest person, they'll realize that they never made that choice, they simply are. I believe it's the same with gay people, and that's why I believe homosexuality, the "gay gene," really does exist. Knowing of the societal marginalization and dangers out and open gay people face in society -- everything from employment discrimination to being killed -- it simply doesn't seem to me as if someone would deliberately choose that for themselves. Biology is destiny.
I will begin by citing the definition of science: the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment. In the following article, you will see for yourselves that neither the X or Y chromosomes contain a gay gene. In the next article I will share, states that there is no gay gene. Is this gene a hoax? By reaching a conclusion from these two articles alone, I can say the gene has been debunked.
People frequently choose a lifestyle that leads to discrimination. Consider any type of a life of crime, from petty theft to serial killer. All criminals are discriminated against by our nations laws. Yet people continue to commit crimes. No one forces them to commit crimes. They do not have a gene that predisposes them to commit crimes. They commit crimes because they want to.