Today was a big day. You, my darling, had your first day at school. When your brother started school I wrote him a letter, just as I do every Christmas and every birthday for each of you. A sort of time capsule in the making that I hope will give you some joy when you are older. I started it when you were babies and I cannot believe that this is my eleventh letter to you.

This letter will be different to the one I wrote your brother two years ago. Partly because you are just different kids. Wonderfully unique and awesome in your own different ways. And partly because every milestone you hit is a bittersweet reminder of your true mettle and a written confirmation that despite dire predictions you are actually here. There was a time when I never thought you would make it past your first minute, hour, day, or week, let alone through five and a half glorious, captivating years watching your personality grow to match the soaring expectations your gargantuan spirit sets.

But there’s another reason this letter is different. I had hoped when you were born – no, actually I had naively believed – that gender would be a non issue because I wouldn’t let it be, and that anything beyond my control would change by the time you were old enough for it to matter. Sadly, I’m more aware than ever of the changes that must happen in the next decade or so if you are to inherit a world that doesn’t discriminate.

So, as well as reminding you that your five year old self is a dreamer whose laugh is contagious, who is kind and smart and who’s sweet demeanour masks a don’t mess with me edge, I also have a job to do in this letter. I know you are a fairy princess in transition right now, stuck between dress ups and huge dreams and wanting so desperately to be a big girl, and that as you grow you will begin to notice the world as it is. In a different, less rosy light.

You will learn one day that some people can’t stop limiting you just because you are a girl. Whether in the language they still use, (throw like a girl), the way they address you, (aren’t you pretty?) or the expectations they have of you, (ladies don’t behave that way dear). These are all sentiments you have already been exposed to. They have already left their mark and there is much more to come.

As you start school you’ll be exposed to many more ideas and opinions- some wonderful, some damaging. I try hard to make sure you know that being born of the female gender doesn’t mean anything other than that. That it doesn’t define you, limit you, or dictate your choices. But as you start school I need you to know something. There are challenges uniquely associated with being a girl. Not because of an inherent lacking on your part but because people aren’t perfect and their perceptions are flawed.

Right now you are fierce. The fiercest. You are tough and formidable. Use it. Keep it. Never be defined by your beauty, but realise that you are beautiful in every way. Always remember you are worthy and deserving. But know too that although you work harder than most, you have a giant, vulnerable heart and others might use it against you. Don’t let them. Fight them. Call out injustice whenever you see it. Not just for yourself but for everyone. Don’t be quiet. In the year when Donald Trump becomes president of the USA, nurturing the spirit of a nasty woman in training has never been more important.

Your real strength is your kindness. You are a thoughtful soul and the world is better for it. We need more people with your ability to care. We need more men and women who start off as children that inherently understand that vulnerability can be strength. Be brave enough to make the same mistakes as boys do – too many girls are conditioned to aspire to perfection instead of true, messy grit and learning through mistakes.

Since you were a newborn I have done my best to steer you away from the pinkifying effect. Neutral onesies. No gender based toys or comments and God help anyone that suggested you were ‘a girly girl.’ This was my attempt to protect you from the inevitable gender biases you have already noticed. And as you grow I’ve seen you defy them. Although you want to be a fairy princess at heart, you still love climbing trees. I was worried the world would turn you all tutus and tiaras without intervention. I should have known you would turn tutus and troublemaking into your own art form. You will need to remember this as you grow. Question all underlying assumptions.

In times of crisis (and make no mistake, the world is in crisis) people often say look for the helpers. You have always been a helper. A person that makes other people’s experiences better. Regardless of gender you have a part to play in this world and you will define it.

I could not be prouder of the kid that you are and the person I see you becoming and I know you won’t take gender bias lying down. Today was one day, but you are on your way. Whatever you do, whichever path you choose I know you will approach it with bravery, kindness and an open heart.