being gay or transgender isn't just a matter of you wake up one day and decide to "give it a try"
actually it is. people choose how they want to behave. there are plenty of cases of people who woke up one day and decided to completely change their life in some way.
it's a lifelong desire to feel correct in your own body; or in the case of gays, the desire to love the people you want to. it doesn't count as a lifestyle choice because it's an attribute that nobody gets to decide and doesn't change.
i have a desire to eat this entire bag of oreos, but i can still choose not to do so. people choose whether or not to act on their urges.
everyone has the choice of how they want to spend their life. if they want to spend their life having love with men or behaving as the opposite gender, they are able to make that choice. there is nothing preventing them from doing the opposite and having love with women and behaving as their own gender as well.