The first step would be to stop using the word "gay" and start using the word homosexual. Once to have committed yourself to this, you will better understand what I have posted.
Before we address the question, let us define what the question is.
Is "being gay" having attractions to members of the same sex or it is acting on these desires? Or, is it becoming part of the gay culture, regardless of the preferences of the person?
As with what is sin, it depends on who you ask, but in reality it only has one definition.
I fail to see how acting flamboyant, having a lisp, or even honestly, carrying a purse would be considered sinful.
Flamboyancy is not homosexual, artwork can be flamboyant. The Church of Saint-Maclou in Rouen, France, is flamboyant. Speaking with a lisp is an impediment. Carrying a purse means your wife’s arms are full from shopping and you don’t want to carry a bunch of stuff you never wanted to purchase in the first place. If people are focusing on these things rather than on what homosexuality really is, they will never, ever understand much of anything about it.
See Kerdy, there is my point. There is something that is called a gay culture, which the acceptance of which is what I call being gay, and just like choosing to do the polka, or jhaving a preference for the Greek food and language, is a choice, and is not inherently sinful(with all the normal constraints of course, such as excess and gluttony)
Now, being homosexual is something else. That implies an attraction to members of the same sex, which could lead to dating, or even being married in the eyes of the law, depending on the laws of the jurisdiction.
I know people who are most assuredly not gay, but are involved in homosexual relationships. Is being gay a choice, of course it is, but, is being homosexual a choice? I honestly do not know the answer to that question.