“There is no one who has not smiled at least once,” writes Marianne LaFrance, a Yale University psychology professor, in her 2011 book “Lip Service: Smiles in Life, Death, Trust, Lies, Work, Memory, Sex and Politics.” Her book explores how smiling unifies us. Like breath, the smile is universal. We smile to connect, to forgive, to love. A smile is beauty, human.

But I have never smiled. Not once.

I was born with Moebius syndrome — a rare form of facial paralysis that results from damage in the womb to the sixth and seventh cranial nerves, which control the muscles of the face. I was born in Britain, on the same day in 1982 the country’s first test-tube twins were born. But while science has created medical miracles like test-tube babies, there’s little that doctors can do for someone with Moebius syndrome.

Decades later, I still cannot smile. Or frown. Or do any of the infinite subtle and not-so-subtle things with my face that I see others in the world around me doing every day.

Doctors describe people with Moebius as having a “mask-like expression.” And that is what strangers must see. A frozen face, eyes unblinking. My mouth always open, motionless, the left corner of my lips slightly lower than the right. Walking down the street, I can feel the touch of casual observers’ eyes.

A child’s very first “social smile” usually occurs six to eight weeks after birth, eagerly awaited by new parents. Because, as an infant, my face remained so expressionless, when I began laughing it took my mother a while to realize that the sound I was making was laughter. At what point, I wonder, did I begin to compensate for the absence of my smile.

I am constantly touching my own face, making it move with my hands. I like the sensation of my fingertips shifting my otherwise motionless lips. It’s something I’ve done since I was very young.

I remember, age 5, kneeling at my grandmother’s dressing table, while my grandmother, without my noticing her, watched from around the doorjamb. Very quietly, I leaned toward her mirror, my elbows pressing into the cool granite top and, with two fingers, lifted the corners of my mouth into a tiny smile — a smile I only dared to share with my reflection.

This was the beginning of my understanding that I was different.

Not until I was 16 did Granny tell me that she had been watching me that day, saying, “It broke my heart.”

Through childhood and adolescence, I continued secretly “smiling” at myself in the mirror. Seeing the appearance, however awkward, of a smile on my own face helped me feel better about the day-to-day missed connections with others — schoolmates, girls in my ballet class, or adults on queue in the supermarket — who perhaps wanted to see me smile back at them.

Not smiling is about much more than surface image, though. It takes real stamina. To swallow a mouthful of food, for example, I use a few delicately placed fingers to press my lips closed. After swallowing, I try to lower the helping hand so that it looks as though I am merely brushing a stray crumb from my mouth, hoping no one notices that I do this many, many times more than a normal person would.

Going to sleep is another challenge. Because I can’t voluntarily close my eyelids fully, I have to either hold my eyelids closed with my right forefinger and thumb until they stay shut, or lie on my back with a cotton tank top laid over my eyes in such a way that their lids are sealed. Sometimes this gets exhausting. Sometimes I shed tears, and that speeds up the process.

I try to act around my disability. To pass. The one missing gesture I can never fully compensate for, though, is smiling. My body feels the smiles my face has never shown. When I explain to new friends why I don’t — can’t — smile, they say, Wow, that must be really hard. Not really, I lie, by now I’m used to it.

Still, there are moments when I feel the smile my face cannot physically make. It might be while I’m laughing over a shared joke with a friend, or when a child passing on the street smiles up at me. It translates as instantaneous pleasure throughout my whole body — a kind of minute awakening, both within and without. For a long time I wondered whether it showed. But close friends tell me my smile does come through, that they can see my smile.

Yet, recently, an elderly man passing me at a bus stop looked me up and down, caught my eye, and said, “Pretty girls are supposed to smile.”

I was speechless. I shook my head and laughed uncomfortably, hoping he wouldn’t pursue the subject. As he walked away, I remembered a high school photographer cheerily calling “Smile!” just before the blinding white flash. “Smile,” someone says, and again I’m 5 in the mirror, or 16, cringing, trying to do something I cannot do, and waiting for the uncomfortable moment to pass.

Effy Redman, a graduate of Hunter College’s creative writing M.F.A. program, lives in Saratoga Springs, N.Y.