My nineteen year old twin sister may not have known that I was in the house, because I saw her walk naked from the bath room to her bed room. The rooms are far apart, so I had the opportunity to watch her for a long time. She had become a beautiful young woman.

She saw me looking at her when she walked, and looked surprised. When she got dressed, and left her bed room, she was blushing. I tried to hide my arousal, while thinking I should not feel that way about my sister.

Because our father is in the military our family moves around a lot. My family consists of my parents, my twin sister, and me. Because my mother is a registered nurse, and because there is a shortage of nurses, my mother has always been able to get a job where my father was stationed.

My sister and I turned nineteen when the COVID 19 pandemic began. Soon after the beginning of the pandemic, Dad left on a mission somewhere. Before leaving he told us not to ask about it, and not to tell anyone about it. Because of the COVID 19 pandemic my mother was doing a lot of overtime at the hospital where she works. Much was closed during the pandemic, including college, so my sister and I spent most of our time alone together in the house.

The house we live in has a swimming pool in the back yard. The back yard is surrounded by a thick row of cedar trees, so no one can watch my sister and I play together in the swimming pool.

For the swimming pool my sister bought a very revealing string bikini that she bought with the money I gave her for her nineteenth birthday. The bottom part barely covers her vulva, so she shaved her bikini area. The imprint of her slit shows thru the thin fabric of the bottom part. The top part only consists of two patches of the same thin fabric that do little more than cover my sister’s nipples. These also show through the fabric.

My sister’s bikini made me feel uncomfortable, but I was glad that no other men have seen her wearing it. My sister’s choice of a bathing suit surprised me, because she is usually shy and modest. I guessed she thought that because I am her brother, it did not matter. Perhaps she thought it did matter, and she wished to reveal to me a side of her personality and character she thought was best concealed from other people.

Because our family moves around a lot, my sister and I have not had time to make many friends. She has always been my best friend, and is often my only friend. Thus we are very close, and confide in each other. We knew that we were both virgins. I told her that I had been impotent with two women I dated in college who wanted to have sex with me.

“They were pretty, and I liked them a lot,” I told my sister. “I took them to nice places, and treated them well, but I wasn’t able to give them everything they wanted from me. Impotence is humiliating. It makes a boy wonder if he is really a man.”

“Maybe you didn’t love them,” my sister suggested.

“That must be it,” I said. “You’re the only woman I love.”

“And you’re the only man I love,” my sister said. “If I date a man who asks me to have sex with him I stop dating him.”

“I’m glad.” I said. “That is what you should do. I love having a beautiful, virgin sister.”

“Thank you,” my sister said, smiling.

“And you are beautiful,” I told her. “Your face is elegant, graceful, and projects intelligence along with innocence. Your eyes are a beautiful shade of blue. Your hair is long, and your arms are thin. Your breasts are large, round, and firm. Your waist is delightfully narrow, and your belly is flat. Your rounded hips beautifully frame your vulva. Your thighs are slender and athletic. Your skin has a delightful, light shade of pink. Your flesh is soft and rounded. Everything about you arouses love and desire.”

My sister blushed slightly. “Thank you,” she said. “You’re a bit too explicit. You look good too with all your weight training.”

“Your string bikini leaves nothing to the imagination,” I said, “I am glad other men don’t see you in that.”

“I wouldn’t wear it in front of other men,” my sister said. “I bought that bikini for your eyes only. I knew you’d like it. I like the way you look at me when I wear it.”

“I like the way you look when you wear it,” I said.

“I like having a virgin sibling too,” my sister said. “Those women couldn’t have loved you as much as I do. I am glad you were impotent with them. I want to keep the other women away from you, so I can enjoy you myself.”

In addition to playing in the swimming pool, my sister and I play at wrestling. I do not exploit my strength advantage. I appreciate the opportunity to feel my sister’s smooth skin and soft flesh.

Once I accidentally pulled her bikini bottom down to her thighs. She angrily pulled it back up, and went inside. My sister liked to flirt with me and tease me, but she got angry when boundaries were crossed.

When we were having dinner together that evening I asked her, “Why’d you get angry at me and go inside?’

“You pulled down my bikini bottom,” she answered.

“It was an accident, but I’m glad it happened,” I said. “I enjoyed looking at your smoothly shaved vulva. You are beautiful down there. You have a slight mound, a well defined slit, and no clit hood. That is as good as it gets. No one else saw. A woman shouldn’t be embarrassed to be seen naked by her brother, especially if he loves her as much as I love you.”

“I was still embarrassed,” my sister said.

For me sexual desire is a complex matter. I cannot desire a woman unless I love her. Nevertheless, sexual desire for me is part of a number of more complex emotions, which restrain desire. My feelings toward my sister fluctuated between the incest taboo, to a desire to make love to her, and back again to the incest taboo.

I did not want to get my sister pregnant. Children of incest frequently have serious genetic defects. Sometimes they are still born or die prematurely. The incest taboo evolved for a reason. It is more than a social convention. It is an instinct, and one I feel, along with the desire I cannot deny.

My sister may have felt the same way about me. One day when we were playing together in the swimming pool she was unusually receptive. I knew our mother would be staying at her hospital for the night. When we came inside from the swimming pool, I got a towel and a condom, and walked into my sister’s bed room. She had not locked the door. She was standing in the middle of her bed room, thinking about which day clothes to change into, and completely naked.

“Please leave!” she pleaded.

“Say it like you want me to,” I replied smiling. I put down the towel and condom, and walking over to my sister. I held her gently, kissing her lips for the first time in my life.