Gigi Hadid and Bella Hadid
PARIS, FRANCE - NOVEMBER 30: L-R) Gigi Hadid and Bella Hadid pose backstage prior to the Victoria's Secret Fashion Show on November 30, 2016 in Paris, France. Pascal Le Segretain/Getty Images for Victoria's Secret

Days after the Kardashian sisters posed in their underwear in a Calvin Klein ad campaign, British Vogue unveiled a monochrome photo featuring Gigi and Bella Hadid huddled together in the nude. And the photoshoots have sparked a debate about why the fashion industry seems obsessed with sexualising sisters.

This isn't the first time that the Hadids or the Kardashians have modelled for photoshoots that seem to suggest a sisterly love that could become sexually charged as soon as the camera turns away. This comes against a backdrop of fauxcest adult films being one of the most searched for categories on Porn Hub in 2017.

Of course, the idea of "hot sisters hooking up" seen through the lens of the male gaze is nothing new. In fact in 2015, both sets of siblings appeared in an ad campaign for the French fashion house Balmain, which also featured model Joan Smalls and her sister Erika. That similarly suggestively blurred the line between platonic love and incest, as Kylie Jenner appeared to grab Kendall's breast.

Another shoot for V magazine with Gigi and Bella - captured when they were aged 19 and 18, respectively - tapped into the same trope. It's also worth noting that all of these shoots were captured by men in their 40s. Not convinced something strange is going on? Then imagine for a second the reaction to a shoot featuring Ben and Casey Affleck or posing holding hands in their underwear.

The images divided fans online . "Umm... can we just please not deny that this is weird. Sisters don't sit like this," wrote one person on Instagram.

"Terrible and creepy", chimed another.

"This makes me uncomfortable..... I feel like I shouldn't have seen this photo. #inappropriate," one user wrote. Another agreed: "I don't understand the incestuous selling point between sisters like these girls or all the Kardashians rolling around in their boy panties together for Calvin Klein. Just weird."

But some praised the image as "arty". One Instagram user argued: "you must have a disturb mind to be disturb by this."

"It's a lot of people's fantasies to see two sisters looking sultrily down a camera," psychologist and feminist commentator Emma Kenny told IBTimes UK. "There is nothing wrong with women being naked as women together. Women feeling comfortable to be naked should be celebrated. But when it's two naked women coming onto the camera, we try to pretend it's artistic because you can't see anything. But it's about the subtext. These women are naked and available and sisters, and it's a fantasy that the popular media shouldn't play into."

Adding that she believes that sexual fantasies are healthy and normal, she added: "There is such a gender bias. We don't have two brothers sat naked looking at each other with a sexual come-on view because men don't do that. Men are valued for different things."

A 2015 shoot featuring Bella and Gigi Hadid for V magazine.