It is her way of imposing logic on an unpredictable world. I can only hope, for her sake, that it all goes according to plan.
Well, it's a tricky thing, age. These days it happens earlier and earlier or later and later. First it was my daughter who, when she was not quite four, announced that she was "over the Spice Girls". Then it was my closest friend, who summoned me for a crisis conference. She is a week younger than me. We have been constant companions for nearly 30 years. She had just woken up and discovered that she was 43 and not, as she had always believed, 27. Surely not, I said. That's middle-aged. Well, OK, so our waists aren't quite what they used to be, and slip-dresses are the work of the devil. Otherwise, nothing much else has changed.
Perhaps, she said, it happens when you're 50? No, I said. Look at Betty. She wears black leather, drives a convertible and is the most glamorous thing I've ever seen. Then there's Jeannie, who stomps around the place in Miyake and Doctor Martens, or June, who's 60 for God's sake, and still slides into a pair of Levi 501's (orange tab, please) and a white T-shirt.
These people aren't middle-aged. But nor are they, in that new media expression, "middle youth". Was there ever a blander or more patronising phrase?
Middle-class, middle-aged, Middle England, middle-brow, middle of the road. Oh, dull. Oh dull and duller. It's so English, that phrase, so terribly embarrassed. You can hear them in conference, can't you? For God's sake don't mention the O word. Well, I suppose it's better than "young at heart", which is downright simpering, but even so I haven't the faintest idea what it really means. I think it's intended to describe the over-thirties which, in the Peter Pan world of magazine publishing, is considered to be "mature". Certainly there's a lot of guff that goes with it, about women "knowing their own minds" (as opposed to whose?) and making "independent choices", but really the exciting new magazines being launched into the market of middle youth are no more than the same tired formula given a glossy make-over - all frocks, cooking and gardening.
You know what's wrong with women's magazines for the over-thirties - (publishers still can't get their tongues around the f-word). No grit. No humour. No rigour. No bloody style. They're so cosy, made for a generation who seem metaphorically to be preparing to get their slippers on. Which, believe me, we are not. We're no different from the women we used to be. OK, so we're 20 years older, and it's our age that's doing their heads in. Middle age is just not - to borrow the current Blair soundbite - sexy. Well, we may be in our forties and fifties but we still wear Gaultier, Lang, Demeulemeester and Joseph, read everything from experimental new fiction to cookbooks, can spot an Alessi at 50 paces, and surf the Web.
Which makes us both a market ripe for exploitation, and a problem. The demographic number-crunchers just can't get their heads around the old, banal cliches of middle age. We confuse them. Elle and Marie Claire may be way too young for us, but magazines that tell us how to crochet a centre-piece for a table or disguise a thickening waist with clever accessories are just way too old.
And it's not only magazine publishers who are confused. I use the example simply because every time I meet a publisher, he or she tells me they're thinking of launching a new title for women who are, well, older. I know, I know, it's hard to get the word out. "What exactly is it you want?" asked one (man) in frustration. Wrong question. In my days on women's magazines you never asked a potential reader what they wanted. You asked them what they didn't want.
To be fair, things have improved a little. Ten years ago, women like me were referred to as "the grey market". In those days, women ceased to exist past the age of 35, or certainly weren't considered worth wooing. AB18-35 was the magic formula. For those not conversant with the lingo, AB means rich, 18-35 means young. The 35, by the way, was always a myth. No matter what they said, 25 was what they meant. In the magazine world, past 35 you stayed at home, knocked up gourmet meals out of leftovers and wore bright colours in clashing patterns - preferably home-made, so that they could slip a little bonus of a paper pattern in between the pages, or one of those interminable knitting patterns. That woman, whoever she was, no longer exists.
And nor does middle age, if my contemporaries are anything to go by. Which is why it's such a dreadful problem for an industry dominated by statistics and neat little soundbites. If they can't nail us with a couple of words, how are they going to sell to us? And it's not just magazines that are suffering. It's anybody who wants to advertise their product - which pretty well takes in most of the world.
Not only do we earn our own money and spend it, but we're more likely to dictate how the communal family pot is distributed than are our men. We either left having kids until late, and so are well established in the top rank of our careers; or we had kids when we were young, so they are now grown-up and independent. As for mortgages, well, we have those too, and the houses and gardens that go with them.
I know this much. Our time will come. When I first started writing about fashion for a Sunday newspaper, back in the early Eighties, I was there under sufferance - shoved into a corner, with three column inches if I was lucky. Well, just look how things have changed.
As for women's issues, they were relegated to the women's pages, edged around with the odd recipe or tip for home improvement. These days, Sunday newspapers are almost nothing but women's pages, with the odd bit of news coverage thrown in for light relief. Then there were men's magazines - or rather, there weren't. I know, it's hard to believe, but until Nick Logan came along with Arena, there wasn't a single one. Now they're across the news stands like a rash.
It doesn't take a genius to spot what's next. Us. I think my daughter has it right. Forget middle age. We are the new young-old.