We are all both sexes

Each of us is more or less both male and female.

We are all XX XYGerald N. Callahan, Colorado State University:
“When I started doing research on the biology of sex development, one of the things that I realized is that the process is controlled by a series of enzymes and the reaction may be more or less complete.”

“Just like with every other human trait, there are an infinite number of possibilities.”

So in essence you’d like for people to think of [male or female] sex in the same way that we think of hair color, or eye color, or other sorts of physiological traits.

Exactly. We might say two people have brown eyes but that doesn’t mean that they’re brown in exactly the same way, or what is seen through those eyes is the same.