Amy is surprised when her six-year-old son, Luke, claims that he has found his twin sister at school. He’s an only child, and it makes no sense. But then the kids get together for a playdate, and Amy discovers that the family tree is bigger than she thought. For years, my life with Jeff was just a dream come true. We had our little family, our careers, and a routine that, while occasionally monotonous, was ours and filled with love. Luke, our son, brought endless joy into our lives — and I wouldn’t have traded family time for date nights at all. Now, we sit around the coffee table, building different things with Lego blocks and eating ice cream. It was everything I had ever wanted my family to look like. Luke is six years old and brimming with the innocent curiosity of childhood. Every afternoon, when he gets home from school — he has a snack and tells me all about his day. Today, his conversation topic was something that puzzled me. Luke was sitting in the kitchen across from me, eating a peanut butter and jelly sandwich while I prepared dinner, working in between. “Mom,” Luke said. “I swear…”What did we say about swearing?” I asked him. “Mom,” he dragged on. “I’m telling you, Luna is my twin sister!”

My son’s declaration caught me completely off guard. “Luke,” I said, masking my confusion with a smile. “You’re an only child, honey. “No, Mom! I’m serious. Luna and I have the same birthday, and we look alike. The teachers think that we’re twins, too. “I continued to cook dinner while watching Luke pick up a crayon. Throughout dinner, Luke was persistent. He spoke about Luna the entire time, talking about what she liked to wear and that she preferred to keep her hair in braids or pigtails. And that she adored swimming. “Mom, she’s great. You’ll like her!” he said, sipping on his juice box. Jeff wasn’t home from work yet, so I was on sole Luke duty. And the longer my son spoke about Luna, the more convinced I was that she was special to him. “Do you think you have a photo of Luna?” I asked Luke as I was doing the dishes. He ran to his bedroom and brought out his class photo — of course, I had seen the photo before, but I only had eyes for my son’s goofy smile and crinkled nose in the photo. I couldn’t remember paying attention to anyone other than Luke. But when he showed me the class photo, pointing out a girl who bore an uncanny resemblance, not just to Luke but to my mother-in-law in her youth, my heart sank. The resemblance to Luke was one thing. But to Jeff’s mother? That was undeniable, and Luke’s joy at his discovery of a ‘long-lost sibling’ only deepened my sense of dread. “Why don’t we invite Luna over?” I asked Luke. “If her mom is okay with it, then you two can have a playdate. “Luke’s eyes shone as he slid into bed, taking his teddy bear with him. “Do you think she’ll come?” Luke asked. “Like really come over? “I’ll speak to her mom tomorrow when I drop you off,” I said, settling in for story time. By the time Jeff came home, he was too tired for me to tell him all about Luke and his mysterious “sister.” He had his dinner and went straight to bed. I struggled to sleep the entire night. I went down a rabbit hole on the internet, trying to find reasons for children to look like each other. I read about doppelgängers and other strange phenomena. The longer I read through articles, the more freaked out I got. Eventually, I went to the kitchen to make myself a cup of tea — anything to soothe my nerves. I knew that the only other explanation was Jeff — that perhaps Luna had something to do with him. But as I twirled my wedding ring around my finger, I knew that I couldn’t doubt Jeff. Since we had been married, my husband doted on me. Throughout my pregnancy, he was everything. He did everything — from drives for late-night cravings to cleaning the shower because I couldn’t do it myself. So, how could I suspect my husband? I continued to read more articles. The following morning, I met Luna’s mother, Penelope, and we arranged the playdate for the kids. “Luna talks about Luke all the time, Amy,” she said. “This will be great for them to spend time together outside of school. “On the day Luna and Penelope showed up, Luke and I baked fresh cookies, and he cleaned up his room. “What’s going on?” Jeff asked. “We’re having people over? “Although I wanted to tell him about Luna the day after Luke showed me his class photo, something in me wanted to keep it silent. I couldn’t understand why my body was trying to convince me that Jeff had something to do. But if I had to admit it, I think I just needed to see what his reaction would be when Luna and her mother walked through the door. That would tell me everything I needed to know. When the doorbell rang, Luke ran off to open it, Jeff and I right behind him. Jeff’s reaction upon seeing the little girl was a picture of guilt, the color draining from his face as Luna ran towards him with open arms. “Daddy!” she cried, holding Jeff around his neck. “I told you she was my sister!” Luke shouted, grabbing my hand in excitement. I looked at Penelope, her eyes wide. The room seemed to spin around me. Jeff told the kids to help themselves to the cookies and play outside, and that the adults needed to talk to each other. The truth spilled out not long after, in a confession that felt more like a betrayal. “It was a long time ago, Mary,” he said. “Well, it was just before we found out that you were pregnant with Luke. “As if that made it any better? I thought to myself, Jeff’s one night of indiscretion, a secret daughter, years of lies — it all came pouring out in a flood of apologies that felt empty and much too late.