Normally it’s pretty easy to know what to do as a parent – they’re good, you praise them, they’re naughty, you punish them. This is just as true with new behaviours as old, because you generally expect the ways they behave, either as a natural part of child development or an extension of your own personality. They start to bite? You know how to deal with that. They hit you? You hit them right back (joking!).

However, my three-year-old’s recent behaviour has thrown me through a loop, because it’s so unexpected I have no idea how I feel about it and, consequently, no idea how to treat it. It’s just so naughty yet so gosh-darned smart I can’t help but admire it, and as it’s the first truly individual expression of her own personality, I don’t really want to squash it.

For at least a year now, my daughter has not been allowed a dummy, so imagine my surprise when I checked on her in the middle of the night to discover her asleep with a dummy in her mouth, only to have that dummy disappear by morning. This happened two or three nights in a row – no dummy at bedtime, no dummy in the morning, but a dummy in the middle of the night – so I casually asked her about it over breakfast.

‘Oh,’ she said. ‘That’s my secret dummy.’

‘Your secret dummy?’ I asked.

She nodded. ‘I keep it in a secret place.’

‘You know you’re not allowed dummies, right?’

‘I know, but it’s my secret dummy,’ she said, ‘and I only use it when I need to.’

Well, what the hell can you say to that? She’s not allowed a dummy, but the fact that she has a secret life that goes on unobserved by her parents, an independent little three-year-old world that’s entirely hers, is crazily advanced and individualistic, and I’d feel like a real meanie taking that away from her.

Also, I have no idea where she hides it!

This strange, devious streak infuses much of her behaviour. If I tell her she has to eat her dinner before she can have pudding, she’ll dutifully clear her plate. We’ll have a great evening, and then after I’ve put her to bed, I’ll start to tidy and discover her dinner hidden under a cushion or on a shelf. I’ve also caught her slipping food onto her sister’s plate, since my youngest – aka The Hoover – will scoff it down before anyone notices.

She’s also cunning with her excuses. Not when she blames her sixteen-month-old sister for things, or says she has her sister’s permission, or that her sister, who can’t talk yet, told her to – because that’s pretty easy to see-through. But some of her excuses are so, well, plausible, I sometimes wonder who’s the one being unreasonable.

Last night, for example, I caught her drawing on the walls with a set of coloured lip  salves she got for Christmas. Of course, I hit the freaking roof. But her excuse? On an episode of the TV programme Bing, they paint a rainbow on Sula’s wall to make the room pretty, and she thought she’d make it pretty for us as a nice surprise. She knows she’s not allowed to draw on the walls with pens or pencils or crayons, which is why she did it with coloured lip balm. And doesn’t it look nice?

Oh. Well, when you put it like that, it doesn’t seem quite so unreasonable. In fact, punishing you for it is what seems unreasonable. So, like, don’t do it again, okay?

And that’s happening every day at the moment. I look at my daughter and think, Aren’t I supposed to be telling you off right now? I’m not even sure myself. Maybe that’s a good thing.

Or maybe it means she’s winning.