Everyone's favourite dieting guru and carb-botherer Gwyneth Paltrow came under fire this week, but surprisingly it wasn't for putting her children on an elimination diet (do you feed your offspring eggs, wheat or deep-water fish? Can you name a deep-water fish? No? Shame on you!) but for selling a bikini designed for pre-teen girls on her alluringly named website, Goop.

The offending article, which is the result of a collaboration between Paltrow and renowned beachwear designer Melissa Odabash, is a plain black triangle top with matching bottoms; pretty inoffensive in itself, you might wager. However, a considerable amount of people, including those at the charity Kidscape, weighed in on how offensive they found the bikinis. To quote from Kidscape's statement, it was that the swimwear contributed to the "trend" of the "sexualisation of children and of childhood" that made it so distasteful.

Your response was probably along the lines of: what was Paltrow thinking? Why is this item of clothing necessary? There's surely nothing wrong with letting girls run around on the beach in just bikini bottoms, based on the fact that they have nothing more to cover up than their male counterparts at that age. Adding a "top half" creates a wholly unnecessary gender divide in young children.

But the real issue is why we see the bikini as inherently sexual in the first place. Is it really that different from a swimming costume? There's little physical difference. So why, while a swimming costume or bottoms are safe and desexualised, is a bikini quite the opposite?

Although invented in 1946, the titillating two-piece was always destined for a highly charged existence, named as it was after the Bikini Atoll: part of the Pacific Proving Grounds where the US went on to test its nuclear weapons. The man we have to thank for the design is Frenchman Louis Réard, who advertised his invention as "the world's smallest bathing suit" and boasted that it was not a true bikini unless it could be pulled through a wedding ring.

The US managed to resist the allure of the bikini until the 1960s, when everybody headed to the seaside and the Beach Boys and Brian Hyland (of Itsy Bitsy Teenie Weenie Yellow Polka-Dot Bikini fame) dominated car radios along the west coast in the run-up to the sexual liberation of the Summer of Love. With all this in mind, isn't the notion of the bikini as a celebration of women's emancipation rather last century?

When I visit my local swimming pool to huff and puff my way through 50 lengths of front crawl, I'm not worrying about my rights as a woman, but more whether I can get in and out before all the local kids finish school and descend in all their float-bashing and backstroke-thrashing glory. And yet I would never dream of heading to the pool in anything less than a sensible swimsuit, despite the notion of a "no bikinis" sign on the wall seeming even more outdated than a "no running, bombing or petting" cartoon.

I wear my swimsuit because it's a disclaimer against the male gaze, an "I'm not wearing anything provocative, so leave me be" insignia that deflects all accusations of "flaunting my curves". Even though I know the notion of the bikini as a sexual object is about as atomic as a Blondie tribute act these days, it remains stuffed in the back of my sock drawer until the holidays (and the promise of a foreign beach) draw near.

Surely the problem is that society deems it okay to see a woman as sexed up when she sits by the pool in a bikini, whereas the guy next to her in his budgie smugglers gets no such appraisal? Of course, the sexualisation of young girls is a real problem, but the mini adults that we see drowning in make-up as they stagger around in their heels at a beauty pageant are a far cry from a child on the beach in her swimming gear, whether that consists of a bikini or a Victorian bathing suit complete with pantaloons.

To move forward in the way that we view women and girls, we need to stop equating not covering up with being sexually available. When seen in this light, the old chestnut of "she was asking to be raped by wearing that short skirt" doesn't seem so far away from this beached whale of a problem. So instead of policing what children wear on the beach, or what women wear in the pool, we need to concentrate on changing society's perception of what bare skin means. After all, the bikini Goop is touting is most offensive for its $45 price tag; good luck justifying that on a cost-per-wear basis in a chlorinated pool, even if your elimination diet has halved your weekly food bill.