Fashion icons are getting younger and younger. Like, really young. This week The Cut profiled Alonso Mateo, the Instagram star who posts Sartorialist-worthy images of himself dressed in designers including Dior and Gucci to his 120,000 followers and whose age you could count on one hand. Yep, he’s five – you’ve probably got jumpers older than that, but you can be that his are more expensive, and more expertly, if not creepily styled.

Oddly though, this immaculately dressed child-man isn’t such an anomaly. At the men’s shows in Milan this week, designer duo DSquared closed their catwalk presentation with a pair of pre-teens dressed in suits that would look more at home on someone double their combined age, and not so long ago, outrage unsurprisingly ensued when French Vogue cast 10 year old Thylane Loubry Blondeau in a seductive shoot. The frequency with which models born post Y2K are cast has even led to a parody Pinterest board, My Imaginery Well-Dressed Toddler Daughter, on which weird-youthful fashion images from around the internet are accompanied by hilarious commentary detailing the stylish life of the fictional, Quinoa.

Sure, fashion’s a young industry – some of today’s big players were probably born when the average Net-a-Porter addict was busy fighting over whether Blur or Oasis were cooler, but at least Tavi’s chameleon hair and ramshackle styling, characteristic of all normal teens, betray her youth. And young actresses like Elle Fanning and Chloe Moretz are more often seen in hoodies and trainers than the grown-up get-up they wear on the red carpet. 

On the flipside though, there’s another group whose ability to dress their age is seriously out of whack. Girls star, writer and director, Lena Dunham, might have some highly credible adult accolades to her name, including Golden Globes, a multi-million dollar book deal and a regular slot on the mast-head of the New Yorker, but that doesn’t stop her dressing in a style younger than her 27 years (off-screen as well as on). This isn't mutton-as-lamb territory, it's adult-as-amoeba.

Dunham's just one of many girls, that also includes Alexa Chung and Tennessee Thomas, who are living out a Virgin Suicides style-dream, in a sepia haze of Peter Pan collars, broderie anglaise and T-bar shoes, despite all being around the 30 mark. It’s admittedly way less creepy when adults dress like kids, but it does make you wonder what the age limit on certain items of clothing is. Will a doll-like dress still look cute, or just plain weird at 40? Meanwhile, fashion writer Lynn Yaeger blows them all out of the water by dressing like a toddler on purpose.

One thing's for sure: there are two very famous babies just around the corner – one so fashion its name was approved by Anna Wintour, and another that despite still being in utero has sparked speculation around what it will wear – that are bound to bring the average age of the style set down another decade or so.