Not necessarily. All men have a G-spot up their anus. That is why some of the guys on here have been saying that it felt good and helped them cum more. It is the only way for a gay guy to have penetrative sex with another which is why the assumption that it is only for gays arose. I know a guy who asked his gf to stick her finger up his arse while they had sex cos he likes it. Its down to personal preference at the end of the day, not just sexual orientation.
~ The journey of a thousand miles begins with a single step ~
* Nothing in the world has ever been accomplished without passion *