I have a coloring book in front of me. It’s called Finding Gender, and it was sent to me by an activist who knows how much I love social justice and felt-tip pens. In the book, a small child and a robot go on marvellous adventures, and children and nostalgic adults get to scribble on their clothes and costumes, their hair and toys. It’s an ordinary colouring book in every respect, apart from the fact that the child isn’t identifiably male or female. Neither is the robot. The person with the crayons gets to decide what they’re wearing, whether they’re boys or girls, or both or neither.

This is how it happens. From dinner-table conversations to children’s books, the lines of gender are being redrawn. Suddenly, transsexual and transgender people—those who do not identify with the sex they were assigned at birth—are everywhere in popular culture. Suddenly, people who transitioning from male to female, or from female to male, or who choose to live outside the gender binary entirely, are no longer universally portrayed as freaks to be gawked at or figures of fun, but as exactly what they have been throughout human history—real, flesh-and-breath people with feelings and dreams that matter.

This month, Time magazine published a cover story titled "The Transgender Tipping Point." The trend-hungry American press is toppling over with spurious tipping points, but this one is real, and it’s important. Centuries of marginalization mean that the statistics are still shaky, but it is estimated that between 0.1 and 5 percent of the population of earth is trans, genderqueer, or intersex. Whichever way you slice it, that’s millions of human beings. As a species, we have come up with space travel, antibiotics, so it seems rather archaic that so much of our culture, from money and fashion, love and family is still ordered around the idea that people come in two kinds based roughly on the contents of their underpants.

Something enormous is happening in our culture. In the past three years, and especially in the past twelve months, a great many transsexual celebrities, actors and activists have exploded into the public sphere. Some of have taken the brave step of disclosing their trans status after they were already household names, like American presenter Janet Mock, rockstar Laura Jane Grace, athlete Fallon Fox, Oscar-winning director Lana Wachowski or activist and former soldier Chelsea Manning. Others have simply become successful without hiding or apologising for their trans status, like sassy British columnist Paris Lees, or actress Laverne Cox, star of "Orange Is The New Black," who graced the Time cover as one of a new generation of breakout trans stars.

At the same time, the internet is making it easier for members of a previously isolated section of the population to find and support one another. Until recently, the threat of violence, coupled with the relatively small visible number of trans people, meant that coming out was a fraught, complicated process. It often meant moving away from your hometown, finding a community in a city, changing your job, your school. Transgender people in isolated or rural areas found it very difficult to make connections with others who might be able to understand their situation and offer advice. A great many trans people waited decades before deciding to transition in public—and some attempted to keep that part of their lives secret forever, at great personal cost.