Sugar and spice and everything peculiar in their genes that means dressing them is more painful than walking across hot coals - that's what little girls are made of.
I don't know what has happened to my formerly cherubic little girl of late. What I do know is that in the place of a quirky, cute little button has emerged a feisty fusspot who can have meltdowns that would put Linda Blair in The Exorcist to shame.
The downwards slide in sweetness could be witnessed about two weeks ago, when suddenly, without warning, dressing her in the morning became a battle of wills that would usually end with me fuming in the kitchen and her sobbing triumphantly and demanding to go to kindy in her birthday suit.
It was when the weather started turning cool and I was getting a little sick of her barking cough every night, so decided I needed to get a little bit tough and banish all summer clothes from the wardrobe. Not a popular move, needless to say.
Especially for someone who won't wear pants, sweaters, singlets, jackets, or anything that doesn't have a good whack of pink (and preferably, glitter).
I had some warning about this problem because my sister had also had it with her daughter, who would disrobe whenever the fancy took her - in the supermarket, on the street, or anywhere else - in the middle of winter.
She was also exceptionally fussy about what she wore - but in my sister, had an ally in her quest to look super cool. Whereas I would be happy if my daughter wore anything - anything at all - as long as it suited the climate.
We'd battle to get out the door and as soon as she got to kindy she'd rip off the hat, shoes and jacket anyhow.
But it gets worse; she started removing her knickers whenever she got in the car. Then, everything from the waist down. Now, she won't sit in her car seat unless she's absolutely stark naked. I live in fear of the probing questions I will get if I'm ever pulled over by the police.
A worse problem was that of refusing to wear a night nappy. By day, she is perfectly toilet trained, but by night, she's not yet dry. And yet, I'd have to endure an hour-long spectacle if I even approached with a nappy, so in the end I thought perhaps she might be dry and let her be.
The first night led to a dry morning, which was great. And then every night after that, for four nights in a row, I'd have a wet, crying person get into bed with me at about 3.30am and an extra load of washing to do every morning.
Nappy pants are our current compromise and I'm just hoping they manage to do their job until the next inexplicable refusal happens.
The one good thing to come out of this sudden u-turn in behaviour is that often, with my daughter howling like a banshee whenever she's faced with something she doesn't like, her formerly slightly naughty brother now looks like an angel-child by comparison.
And he's not immune to rubbing it in either: "Look mum, she's being naughty again! Mum, can she go straight to bed without TV now she's not eating her veges? Mum, I'm winning because I put on my knickers and she didn't!"
Yes, it would be too much to expect both of them to behave in tandem, I know. And I'm hoping this is just a "terrible twos" phase.
I bear it remembering Ralph Waldo Emerson's famous words: "A child is a curly dimpled lunatic".
I figure once this passes, I have about eight years to brace myself for the next irrational onslaught!