History is written by the winners (Judeo-Christian). Therefore, history has told only the story of vanilla sex being normal throughout history unless you look really hard. I very highly doubt that every culture and everyone has seen vanilla sex as the only acceptable form. I can name a few challenges to this off the top of my head:Gentile said:There was a time when the only real and acceptable form of sex would be your typical vanilla sex between a married man and woman that you see (if you're into voyeurism) in any king sized bed across the land
Pederasty: Probably spelled wrong, but the practice of older males having sex with adolescent males common to the Greeks and Romans
Jains: Pretty early in their history, they wrote what was normal/not normal for sex. This included only actual medical problems
Hinduism: Dude, one God was born from a lesbian couple. This has been played down due to British colonialism
Medieval Islam: I read some pretty racy poetry and plays that were totally gay, and a lot of these haven't been translated due to a paradigm shift due to colonialism. Such instances of literature are very common depending on the era and religion you choose to look at
Medieval Christiandom: There exists some texts on what was punishable for sex (a list of what the Church didn't want you doing) that included modern things such as dildos ^^
Africa: Basically no pre-colonial history, but there is reason to think that lesbian marriages (dowry exchanges) existed prior to colonialism (because how could they come from Europe when it didn't exist there and how would it be a reaction to Europe?)
Two-Spirit and variations: You will actually have a hard time finding a group of people who do not have a place for transgendered or sexual minorities in their society. They are often considered sacred in some way.
Pornography: When we got the printing press, we printed porn. When we got TV, we put porn on it. When we got the Internet, we put porn on it. Porn has been around since FOREVER and we keep looking for a way to show everyone else.
Unmarried: Brothels. And lots of them. Everywhere. Oh, and harems!