A growing number of people refuse to be put into male or female categories, either because they do not identify as male or female, or because they are going through transition to the opposite gender.
Germany, Australia, Nepal and Pakistan now offer a third gender option on official forms with other countries set to follow suit. And scientists are finding more evidence to suggest that even biological sex is a spectrum.
Do we need to re-imagine our binary world and rethink one of the most basic parts of our identity?
Brin Bixby was brought up as a boy, and went on to get married and father children before coming out as bigender. She set up Bigender.net, which reflects the view that gender is a spectrum.
“In college I wore a dress on Halloween, and it was supposed to be a joke, and the people helping me thought it was going to be hyper-real, exaggerated. [But] I didn’t want to be a drag queen, I wanted to be a woman, and I think it took people by surprise.
“It was the first time I looked in the mirror and saw myself. People interacted with me as a woman: they saw me the way I wanted them to.
“I would be most comfortable if I didn’t have to think about my gender, but unfortunately that’s not how it works for me and a lot of other non-binary people.
“We have a cultural understanding of what gender is and looks like, and in the west we have a very binary view of it. My sense of gender as a part of my identity shifts.
“I present as a woman everywhere I go, except for at work and at my children’s school, because it gets very exhausting to have to explain gender fluidity to everyone I meet.
“Ideally we would not make gender such a huge focus of our culture, which would give people the freedom to inhabit their gender in ways that feels most comfortable to them.
“What we’re seeing now is a relaxation of the sense of binary amongst younger people and internet-savvy people who are inhabiting much more fluid spaces.”
Mark Gevisser: Accept the gender continuum
Writer Mark Gevisser explores gender identities across different cultures.
“We know there’s a gender continuum, because there have always been effeminate boys and masculine girls. Transgender is certainly not a western phenomenon. In many cultures all over the world there are traditionally third gender or gender-fluid identities.