I see what ceder is try to get at. Try going back in time 50 years or so and tell people you are gay. Enjoy your jail time.
But there will be things that will NEVER be accepted. Peadophillia for example will be something that is "ok" in society. Incest? Who knows? I don't think so. There will always be that idea of not having enough Grandparents is a bad thing geneticly. Its is bad bad thing geneticly by the way. But as Somedude joked, its a way of life in some parts. Shockingly. Theres probabilly some who would quote Bible verses to support the idea of fucking family members. But lets face it. It ain't right