I should have been clearer: What is usually understood as gay culture is an artificial concept based on stereotypes and disregarding the diversity of people.
Culture is a term interpreted in many different ways and is often misused when we only want to to describe a part of society. As some already said here, culture is so much more. It always annoys me when it's used to separate a group of people from the rest based on one or a few things they have in common.
We tend to surround us with others who are like us, that's natural, it means protection, we feel safe. That's what the early humans did, what animals do, instinct, nature. I understand culture in contrast to nature and I want the big picture, I want to be part of culture, not of xxx-culture or yyy-culture. I am shaped by my surroundings, by my upbringing, by my sexuality and much more, yes, but I will not let myself be boxed in one of these.
Sorry about the rant it has been a sore point for me lately.