My mother is an exhibitionist. Her freedom with her body is beautiful to me, signaling a lack of vanity, a comfort with aging, a kind of joy in the healthy softness of her small frame, which bore all three of my sisters and myself and is just now beginning to show the creped swags of time.

Most mornings in my childhood, my mother’s swimming bag hung from a hook in the laundry room near our backpacks, and we knew that as soon as we caught the school bus, she would take that bag and be gone to swim at the pool in the Hinkson Creek valley. We could imagine her body, small and sheathed, gliding slowly through the water. But hours before that time, we would see her walking down the hallway from the bathroom to the bedroom, a towel in her hair or her hands, naked.

It was practical: we were all girls, our father was no matter; why should she wear a robe? But it felt, too, like a gesture of candor, and I see now that I have somehow linked in my mind the shape and colors of her naked body and the sound of her voice, quiet after a fight, saying, “I’m sorry. Please forgive me.” I could draw you a map of the freckles, the scars, and the diamond-shaped birthmark on the skin of her legs. I could draw you a cloudy map of the sunspots on her back and her arms.

My father, understandably, is more modest. He is a builder, and when I was a child I visited him on job sites and saw him standing amidst pale planks of half-framed houses: brown chest and back, blue jeans, work boots. But he was always dressed at home, or hurrying from the bathroom to the bedroom in a well-wrapped towel.

My sister Julie is a painter. She has been working on a series of paintings about women and men, their bodies, and their need for and confusion over the other. The first painting required two models: a man, clothed, and a woman, unclothed. She recruited two friends to pose separately for her, and in the final painting, the two of them are seated together on a love seat. The woman turns away, a pained look on her face, while the man casts a fraught glance toward her.

Julie told me that the second painting in the series would depict a man and a woman, both unclothed this time, and that the woman would be slumped like a fish, caught in a net. When she was at our parents’ home in Missouri a couple of weeks ago, a friend posed for her as the male character. She did not have time to sketch anyone for the woman.

“Would you be wiling to pose nude for me?” she asked me last week.

I thought about it for a minute. I turned thirty this summer and my body, in a kind of delayed adolescence, finally softened. But I thought of my mother, and of the comfort of real bodies, and I said, “I guess so.”

I didn’t think to tell my husband Ben. Lying in bed together last Thursday night, he asked me what I was doing over the weekend while he worked a thirty-six-hour hospital shift. I told him that, among other things, I was posing for Julie on Saturday morning.

“Posing? Naked?”

“Yes.”

“I don’t know how I feel about that.”

“I won’t do it if you don’t feel comfortable.”

“No, it’s okay,” he said, but I wasn’t sure he meant it.

On Saturday morning, I drove over to the old row house where my sister Julie lives. In the living room, a lamp sat on the floor beside an old green hammock.

I went upstairs and took off my clothes in the cold bathroom. She had me lie in the hammock facing away from her.

“Pull your feet in tight, like you’re cold,” she said, stopping to snap a picture or sketch. “Arch your shoulders a little more. Your toe looks funny; lay your feet on top of each other.”

I had no idea what I looked like from where Julie sat. From where I lay, staring down at my stomach and breasts, my body looked unfamiliar. I still expected to see the small, lean, almost androgynous shape that carried me through most of my life. But it was gone, given up to a softer form.

Julie held up the digital camera so that we could look at the images on its screen. The pictures showed a woman’s full body, white and sloping, the hammock’s net like a topographical map whose grid stretched to show the curve and rise of her figure.

I thought of Song of Songs, the beloved’s body like apples, myrrh, deer, so many ripe, unwieldy things. I thought of Velasquez’s Venus, her body rich and dimpled.

I remembered, too, the long-ago morning when my mother, naked, brushing out her wet hair in the bathroom, heard my father calling her name. His voice echoing up to the second floor was strange, cracking; he called and called for her. As he ran up the stairs, she ran down the dark hallway. They met before the doorway to their room.

I was fifteen years old and I had never seen my father cry. I had never heard him gulp for breath and try to speak between sobs. A friend, a man from our church, had died unexpectedly in the night, and I know now that my father could not take the thought of death coming for a man only half a generation older than him.

My mother took him in her arms, the towel she had tried to grab falling, pinned between their bodies. He clung to her and dropped the phone. I saw her soft stomach breathe and expand like a pillar, and her small breasts lift to brace his chest. As much as I remember his sobs, I remember her taking strength, holding him up.