Alternate Sex Culture
In our world, the primary act around which the majority of sexual interaction revolves is vaginal intercourse. There are outliers and fetishes and foreplay, of course, but in terms of broad cultural understanding, men and women want - to put it as crudely as possible - penis in vagina. Now, what if you changed this primary sex act to something else? This might have a great number of knock-on effects besides just changing men and/or women's preferences. It might affect how the culture views...
Fetish