One of the first things to observe about sex is that our personal experience of sex, as individuals, HAS to be both similar to others and also different.
There are fundamental features of sex that we have in common with others, beginning with the most obvious physical similarities, but extending to other aspects of our being too: for example, our emotional and psychological life.
At the same time, because it involves our own unique personal perception and our "interpretation" of our own experience (how we understand it, how we think about it) -- which is shaped by all our previous experiences and by the lenses through which we look at reality -- our sexual activity has to be unique as well.
We have to do justice to both aspects, not treating sex as if it were purely personal and idiosyncratic or as if everyone's experience were basically the same.
THE STARTING POINT:
EVERYONE IS ALIKE AND . . .
EVERYONE IS DIFFERENT