I blame Levi's. The US denim giant were the go-to brand for jeans in the nineties, hence every woman and her mother had a pair of 501s.
An iconic cut, I think we can all agree, but those three digits were overshadowed by the other numbers on the brown leather tab - the ones that advertise the owner's waist and in-seam measurements. Stamped, filed, indexed and there for the whole world to see.
They say school uniforms prevent competitive and comparative behaviour among schoolchildren. I would agree with school authorities on this one as I can still remember the no-uniform days at my school, an annual event when ankle-length wool skirts and itchy jumpers were replaced with a sea of blue jeans - Levi's, if you had any sense at all.
I learnt fairly quickly that it wasn't enough to just own a pair of Levi's. They had to be a certain size of Levi's too.
Today I couldn't tell you how to measure the circumference of a circle or the volume of a hemisphere, but seared in my memory is the average waist measurement of my fellow students - 28 inches, seeing as you're asking.
Twenty-eight was the magic number, although there were always whispers about so-and-so having a "25-inch waist" and being "like so obviously anorexic".
I didn't have a 28-inch waist. Through great difficulty, sheer persistence and an unhealthy disregard for urinary tract infections, I somehow squeezed myself into a 29-inch waist - though it generally involved leaving the top button open, and undoing all the buttons after dinner.
And still it wasn't good enough. Oh no, there was so much more to it than just owning a pair of Levi's that proudly showcased the desired waist measurements. They had to look good, too.
The funny thing about jeans is that you never quite know how they look from behind. It's an audacious showcasing of the body when you're essentially blind to the big reveal; akin to standing up and performing for an audience with your back turned to them.
I had a sneaking suspicion that my 29-inch Levi's didn't look as good as they sounded, partly because they cut off my circulation; partly because my thighs took on the shape of butternut squashes when I finally, somehow - with the grace of God... OOOF! - pulled them on.
And also because when walking through a housing estate in Stillorgan, aged 14, a male friend, while staring wistfully at the bottom of my pal, turned to me and said: "She has a great arse."
At that point I realised that 1) I didn't have a great arse; 2) I was the type of woman that men discussed great arses with and 3) that I was fat, or at least very, very chubby.
I took a clandestine peek at my friend's Levi's label later that day: 26/32.
The situation wasn't any better at home, where the perfect night in for me was watching my older sister get ready to go out.
With The Prodigy providing the soundtrack, I'd help her customise her Adidas zip-ups by running neon nail polish along the stripes. And then out would come the false eyelashes, the strappy halternecks and the coveted drainpipe Levi's.
Most men will have a memory of smuggling their schoolmates into their big brother's room to show off their guitar/vinyl collection/computer and basking in the reflected glory.
I showed off my sister's 25-inch Levi's jeans, in the back of my mind hoping that people would conclude that I came from a gene pool that could pull these jeans off.
"Yeah, she's basically a model," I explained as I flicked through the hangers, pulling out spandex cat suits and vests with smiley faces painted on the back of them.
"I sometimes wear this stuff myself," I lied. Though I suspect they didn't believe me, partly because we were often interrupted by the screams of "Get out of my room you fat bitch!"
I never got to wear those drainpipe Levi's, despite my sister's assurances to the contrary (and despite my better attempts).
And I never got down to a 25-inch waist, despite coming from the same gene pool as my sister.
I would later learn that she spent the better part of her teens raving for Ireland so she was wielded something of an unfair advantage.
I went through my own phases: flared jeans, skinny jeans, high-waisted jeans (which I can't help but notice dovetailed with the breakdown of my last serious relationship) and Salsa jeans (essentially a Wonderbra for the bottom).
These days I wear boyfriend jeans, the style du jour. Although mine are not a homage to the boy cut, bought in a women's clothing store.
They are actual boy jeans: 34/36. Preposterously big for my shape, they sit down on the hips and are rolled up at the bottom.
But they are comfortable, and they remind me that I am comfortable in my body, even if I don't have a 28-inch waist.