I suppose it depends on the fraternity, but mine wasn’t gay at all. It was a good group of guys. They even accepted me (obviously I was in the closet regarding my gender), though I was noticeably different. I don’t think I came across as “gay” at all, rather as quiet, withdrawn, secretive, and a heavy drinker. I suspect it was obvious I was hiding something, but no one seemed to assume it was my gender or my sexual orientation (I am a Lesbian).
I told a couple of brothers (who I was closer to) that I was a lesbian. They just smiled and said “yeah, me too.” I didn’t think any of them were serious, and they didn’t seem to consider the possibility that I was serious.