"To my kids, who are always fighting. Here is what you need to know."

My son and daughter were fighting yesterday, in that little kid kind of way. Telling each other how bad they smelled, chasing each other around the house, wrestling on the floor. My son, who is five, loudly proclaimed that he wished he didn’t have a sister.

“Oh, come on,” I told him. “She’s your best friend.”

“No,” he corrected me. “She’s my worst friend.”

My son is too young to appreciate his eight-year-old sister right now. But one day, he’ll realise she’s the best thing that ever happened to him. This is what I want to tell him.

Your sister is your playmate. She’s got the energy to run around and around in circles with you, while I just want to sit back with a glass of wine. She’s as genuinely fascinated by bucketfuls of mud as you are, not pretend-fascinated like I am.

She'll play those boring board games that make me inwardly groan every time you pull them out. She'll leap off the furniture with you, and occasionally onto you, while I'm the no-fun one in the background yelling, "Watch out for the glass door!" She'll laugh at your jokes about bottoms, while I just roll my eyes.

Your sister is your annoyance. She wants exactly the same piece of Lego you do, even though there are 2739 other pieces in the tub. So you learn to fight for want you want, and you learn you can't always get what you want. She teases you, so you learn to tease back, or act like you don't care, even though you do. She headbutts you, so you learn... well, I don't know. That butting heads hurts. Maybe it'll teach you to avoid bar fights.

Here's a video showing the love between siblings. Post continues after video...

Your sister is your ally. She'll sit on me while you tickle me. She'll gang up with you to pester me for a trip to the beach, or a kitten. She'll do all the groundwork of wearing us down as parents, so things will be easier for you as you grow up. She and her friends will teach you that girls aren't some different species, they're just other people.

Your sister is your history. She's the one person who shares your mum and your dad and your childhood. She has your name and your face. She's the one person who'll know you all your life. She'll remember all the Christmas mornings and the road trips and the dogs and the big tree in the backyard. She'll pull out the embarrassing photos. She'll laugh at the lame family jokes.

When I'm gone, you'll still have her. You'll always be able to ring her, any time of the day or night, and tell her your most terrible secret, or just say nothing at all. You'll always be able to drop around to her place, unannounced, and stay for five minutes, or five weeks. She'll get irritated with you, and fight with you, but she'll always have your back. Friends come and go, but brothers and sisters are forever.

You don't know all this yet, but one day you will.

Do your kids fight with each other?