Where does the idea that homosexuality or any sexuality for that matter is a lifestyle come from?

I think this question may have been asked before but as there are a number of new users as of late, I thought I would ask it again.

Many people seem to think that homosexuality, indeed, any non-standard sexuality, is a lifestyle. I have never understood this because sex is a relatively small part of someone’s life and no one’s well, very few people’s life is based on their sex life. I understand that there are some lifestyles of which homosexuality is a large or integral part, but this is not the same as homosexuality being a lifestyle.

I have heard the “choice” argument and I do not think this is a valid argument. Even if you do, please try a different argument if you can. Thank you.