08/09/2016 07:23 BST | Updated 08/09/2017 06:12 BST

Men Don't Have Periods - Women Do

This week, there were Twitter larks imagining what it would be like if men had periods. Using the hashtag #IfMenHadPeriods, one person posted a cartoon of a man spray-painting his name on a wall, using blood shooting out of his penis - tagging his territory like a champ. In the same sketch, another man laughs as he paintballs his mate in the face, with blood cannoning out of his bits. It's a jovial scene, a bit like in Bugsy Malone, but with menstrual blood instead of custard pies.

Someone else posted a spoof advert for Manpons, imagining how tampons would be marketed to men (they'd be designed by NASA scientists and engineered for a super-charged performance). Other tweets included, "we'd have a painkiller that ACTUALLY stopped cramps," and, "there would be a sharp increase in bar fights due to being asked if it was 'that time of the month.'"

It was a bit of fun, but not everyone thought so. One Twitter user wrote, "While this highly cisnormative hashtag is trending, I want to remind everyone that trans men do exist + some have periods." Another complained, "Men do have periods. Not every man is cis and it's disgusting for people to still be assuming that they are." There were numerous other tweets along these lines.

I'm sorry, Social Justice Warriors, but here's the science bit: Men don't have periods - women do. That's biology. It doesn't matter how we identify, what we wear, who we sleep with, or which pronouns we prefer - our reproductive organs simply don't care.

I understand why some women might think the grass is greener as a man. Men get paid more, and they're more likely to be listened to in meetings. They don't tend to get married off as kids to OAPs, and they're not usually the victims of "honour killings." They aren't coerced into wearing burkas, and they usually do less housework. But to paraphrase Girls Aloud, you can't escape your biology. You can't opt out of being a woman.

In May this year, a woman in Iceland who identifies as a transgender man, became pregnant, telling the press, "It was a bit of a shock." But this is what happens when a man - a biological man - ejaculates in a woman's vagina. Those are the reproductive facts, and this case illustrates the confusion between sex and gender.

You cannot choose your sex, and neither can you change it. Gender is a set of stereotypes associated with each sex. They're society's ideas about how men and women should behave, and how they should appear. A woman may prefer the stereotypes associated with being male, but identifying as a man won't stop her getting pregnant, and nor will it necessarily stop men from treating her as a woman, in the very ways she wishes they wouldn't.

In Canada, also in May this year, a woman who identifies as a transgender man was sexually assaulted by a taxi driver. The victim of the assault has been quoted as saying: "I think he just didn't care that I was a trans man... he still continued to call me a woman even though I had explicitly told him I was a male and I had been transitioning for a while." It's almost as if the victim thinks that identifying as male gives her an opt-out from sexual assault, while other women are fair game for it. But it didn't matter how she identified, the taxi driver still recognised her as a woman, and he still sexually assaulted her.

Instead of trying to "opt out" of being a woman, in order to avoid the worst bits, how about working towards a safer and more equal society for everyone - regardless of how they identify. Nobody can actually change sex, but what we can do is challenge the gender stereotypes, and break down the cultural constructions that leave women lying in the wet patch.