Mary Duffy, the plus-size modeling agent, built a career on being proud of being overweight and recruiting other women who felt the same way. But even she seemed of two minds when it came to her uniqueness: On one hand, she was grateful for her natural curviness. On the other, she seemed to dwell on thinness.

In the old days, she told me, it drove her crazy when her models would try to lose weight to fit societal norms. She would often think to herself, I’m so pretty that I can even gain weight and they’ll still pay me three hundred dollars an hour to stand in front of a camera. She devised one-liners to lob at people who made fun of her models because of their weight: “Mattel made the Barbie and God made the rest of us.”

“I’m Irish,” she explained. “If you’re purposely rude to me, I can’t be completely happy until I’ve thrown you into a month of therapy.”

And yet. When I walked into her apartment, practically the first thing she said was, “You’re thin as a pencil!” She asked me whether I was “naturally” that way or if I watch what I eat.

As a young adult, Mary would buy the smallest size she could fit in and would use water pills and lingerie in order to squeeze into it. As she showed me old images of herself in catalogs, she stopped to point to her size-16 frame and say, “My God, I was a large woman.”

Being different can bring about a great deal of ambivalence. Not even those who achieved success because of their difference, as Mary did, were able to escape an occasional inkling that life as someone more traditional might have been better. And many still don’t fit perfectly in one group or the other, instead finding themselves in between two different tribes.

This is especially the case when a person’s difference is the result of physical appearance, which can be altered with surgery, but which is so fundamental to identity. “That’s you!” people say, when they spot you in photos. How could you want to be someone other than yourself, even if the physical manifestation of “you” is not what society prefers?

I encountered these kinds of conflicting feelings about difference when I spoke with Ariel Henley, a writer with a facial disfigurement. Ariel was born with Crouzon syndrome, a disorder in which a fetus’s skull bones don’t fuse properly, resulting in a visibly deformed head and wide-set, bulging eyes. Ariel has undergone many surgeries, but her facial difference is still visible. Her eyes are slightly farther apart than most people’s, and one is slanted downward. Her disfigurement is the subject of much of her writing.