This is a Polaroid of me from around 1981; i asked my mum to dig it out for me, and it is exactly as I remember it – the green jacket, the stiff denim jeans, the little sticker on my ear that I pretended was an earring. I remember how the snake felt in my hands, warm and supple, not cold and slimy as I was expecting. We were visiting a wildlife centre somewhere in the south of England, and if you paid a pound you'd get a Polaroid taken with the snake. My sister did it too.

This is the same sister who we found out last week is carrying a boy – my nephew. She rang me as soon as she left the hospital, and when she said the words i really did scream. A boy! A baby! It's suddenly all feeling very real. So many of my friends have children, you'd think i'd be used to it by now, but this is something different. This is family. This is my sister. We think the same; at times we are the same. And yet now she has embarked on a very different road from me, and it has brought up a lot of stuff.

After she rang me from the hospital, i sat in my chair, reeling. I felt such an intense rush of emotion, it was unexpected and overwhelming. At the heart of it all was love – love for a little baby that i haven't met yet. Now i knew he was a HE and real and on his way, i could feel my heart expand as i took it all in. I could imagine how i'd play with him, and take him to the park, and teach him about girls and buy him the futuristic equivalent of an iPod. I could see Christmases and birthdays with my family gathered round, a family that has been just the three of us for so long. Boyfriends and fiances have found their way into our tiny tribe, but now there's someone new. Someone connected to me by blood.

I was truly happy for my sister when she fell pregnant as i knew that was what she wanted, but at my age you can't help but look at your own life and compare.  I don't know if i will ever have children. In all honesty, i don't know if i want to. The urge comes and goes, often off the back of an assumption of how my life should be unfolding, but when i look into my heart i don't know if motherhood is something i truly want. Maybe if i was in a relationship things would look different (and predictably everyone says that to me all the time) but i know myself well enough by now to know that i see a different path ahead of me, one that has a partner-in-crime, a thriving work life, a chance to explore the world, and a nephew i will dote on. Being an auntie feels like such a gift to be given – when i felt that ache of love for the baby my beautiful sister is carrying, i saw my world take on a new shape. I wonder if anyone has ever written a book about being an auntie – the Art of Auntiehood. How we get the honour of helping bring up a child without the sleepless nights. Now I know someone will visit me* when i'm old and grey and surrounded by cats – my handsome sensitive and talented nephew :)

Maybe all this sounds silly, but it's comforting to get a glimpse into a possible future. After five years of independent living you find yourself existing in the moment more and more, the future a mystery when you don't know who you'll spend it with, if at all. Our society is so wrapped up around the family, around relationships, around 2.4 kids and the school run and the woman in the bank calling me "Mrs Conway" so once again i have to correct her. My 37th birthday is fast approaching and still i do not feel the urge to have a child, and a part of me wonders if my books will be my babies, just as my nephew will be my little pal. The thought of it makes me smile. Whatever happens, I'm sure it will be okay, either way.

* fingers crossed.