A/N: I took some scientific liberties in favor of characterization. I am aware that it's fraternal twins, not identical, that tend to run in families. After workshopping this piece, we decided that it is easier to suspend disbelief in regards to biology than character motivation.
Three-year-old Luke poked his cousin's dimples. She cooed at him and gave him a gummy smile. Her sister also squealed for attention, and Luke tickled her foot. The two girls goo-go-ed and ga-ga-ed at each other and pulled lightly at each other's fingers. Luke stared at them; under the same pink blanket, they almost looked like a multi-headed body arguing with itself.
"Oh Amy, the twins are beautiful!" said Luke's mother. "Identical to the last freckle." She leaned down to brush the hair away from one twin's eyes.
"Not quite identical," said Amy. "Emily has a mole on her butt, just like you. She grinned at Luke's mother, who rolled her eyes.
Luke looked away from the babies and studied his mother. Brown eyes, brown hair, a small, hooked nose. Her long fingers stroked one of the babies' cheeks. Luke looked at Aunt Amy. Brown eyes, brown hair, and she scratched her small hooked nose with her long fingers. The babies cooed in unison; both had blue eyes, thin hair that fell across their foreheads, and the same hooked nose.
"Mommy?" Luke asked. She didn't seem to hear him, and kept talking. Luke turned around and pulled on her skirt to get her attention. "Mommy!" he demanded. She stopped talking and looked down at Luke from her chair.
"Honey, Mommy and Aunt Amy are having grown up talk," she replied, and turned her head away from him.
"Mommy, where's my twin?"
His mother looked up at her sister, slack-jawed. Luke tugged on her skirt again when she still didn't answer him. Her head snapped down when he demanded her attention again. "Luke, you don't have a twin," she said slowly.
"But Andrea is Emily's twin, and Aunt Amy is your twin!" Luke reasoned. "And where's Daddy's twin?"
Luke's mother picked up her son and put him on her lap. "Sweetie," she said, pushing some of his hair behind his ear, "not everyone has a twin."
"Howcome?" Luke demanded. "Can't I get one?"
Aunt Amy giggled and smiled at him. "Luke, remember what your mommy told you when my tummy got really big?"
Luke smiled big and sat up straighter. "She said you were talking special care of my new cousins!" he announced.
Both women smiled at him, and Aunt Amy continued. "Well, when a mommy starts carrying a baby, it starts out really small." She made a tiny circle by curling up her first finger on her thumb. Luke tried to copy her and looked through the small hole.
"Sometimes, before a baby starts to grow, it can split in half, and two babies start growing," Luke's mother explained, and the held up both her hands making the tiny finger-circles.
"Howcome?" asked Luke.
"No one knows, honey," said his mother. "But it happened when Grandma was carrying Mommy and Aunt Amy, and now it happened again when Aunt Amy carried your new cousins."
Luke frowned and cocked his head to the side. "But didn't it happen when you were carrying me?"
His mother closes her eyes for a moment, and she swallows hard before she opens them. "Well, Luke, sometimes the twin doesn't become a real baby."
Luke's excitement increased. "So, I do have a twin, but he's just not real?" he asked.
"No, honey, you don't have a twin," said his mother.
Luke looked down at his small hands. "Oh," he said at last.
"Why don't you go get your teddy for Andrea and Emily to play with?" Aunt Amy suggested.
Luke hopped off her lap and ambled out of the room and ran straight into his father coming home from work. "Daddy, I could have had a twin!" he said, clutching his father's leg. "I wonder what his name would have been."
His father set down his briefcase and patted Luke on the head. "That's great, son," he said. "How about you get your shoes on and I'll take you out on your tricycle?'