[ WP ] You and your mother have lived alone for as long as you can remember . On your 15th birthday , you find out the person you thought was your mother is actually your sister ...

The baby lay on the doorstep, blue eyes wide and curious. It did n't cry, or make a sound. 
 
 `` Mum?'' I called out. `` There's a baby.'' 
 
 `` Bring her in,'' she said, apparently unbothered. I did n't even know how to hold a baby. They had n't covered this in school. I picked up the child, cradling her in my arms, and only then did it occur to me that my mother had known it was a girl. 
 
 She might be wrong, I considered, but I did n't want to check. If I unwrapped the baby I was sure I'd never get her comfortable again. And I did n't want to make her cry. 
 
 I brought her in to the kitchen, where Mum was stirring tea. She'd set up a high chair at the end of the table, and I wondered where she'd got it from. 
 
 `` That's your sister,'' she said quietly, taking a sip from the glass of wine by the oven. 
 
 `` My sister?'' 
 
 She closed her eyes and appeared to steel herself for strength. `` I meant to tell you before.'' 
 
 `` Tell me what?'' 
 
 `` You'll want to sit down.'' 
 
 I sat, keeping the baby tight to my chest, even as her eyes started to close and she drifted off. 
 
 `` You're not my daughter,'' she says. `` Every fifteen years, a baby is delivered to this doorstep by our mother. You'll raise it as your own until her fifteenth birthday.'' 
 
 My stomach plummeted. `` You're not my mother?'' 
 
 My voice cracked on the word mother, a humiliating defeat. 
 
 `` I've never met her,'' she said. `` But I've heard stories. The sister before me, she told me things.'' 
 
 `` How many of us are there?'' I asked. This seemed important, somehow. Vital to the knowledge of who I was. Who my family was. As a child I'd been fascinated by the identity of my father, and had never got the answer I wanted. This, at least, explained why. 
 
 `` I do n't know,'' she said. `` Many. Tens, certainly. All girls.'' 
 
 `` I do n't understand.'' 
 
 `` Nor did I,'' she said. `` But I'll leave you instructions. There's a book, a journal. And I'll come back and visit.'' 
 
 `` Where are you going?'' 
 
 `` She's yours now,'' she said. `` Yours to raise. I'm going on my journey. I'm going to find our mother.'' 
 
 I stared at her blankly, and then down at the tiny pink face beneath me. I was only fifteen. I could n't raise a child. 
 
 But she'd done it. She'd protected me and I loved her. 
 
 `` Do n't leave,'' I said quietly. She shook her head. 
 
 `` I've left everything you need upstairs. Gina, from next door will come and visit tomorrow, if you're confused.'' 
 
 She paused, turned off the oven and picked up her bag from by the door. 
 
 `` You'll learn to love her,'' she said, before she tugged the strap over her shoulder and walked out the door. She posted the key through the slot, a final reminder that she was n't returning. 
 
 And I had a baby in my arms to care for.
