Kristi’s life changed for ever on, of all places, a feminist studies course. She hadn’t done the prior reading, so what she learnt that day in the 1990s, at the age of 19, was a surprise. “I had no idea when I walked into this class, my whole f***ing world was going to come down.”

Trying not to look as if she was unprepared, Kristi began flipping through the book. “I started reading about how some children were born with genitals that fall outside the norm.” The penis is too small, maybe. Or the clitoris too big. When that happens, she read, sometimes the child’s genitals are reconstructed to match more clearly a chosen gender.

Today Kristi, who now goes by Jim, remembers looking at the disgust on the faces all around. “They were thinking, ‘Would they just mutilate babies?’ And it just hit me: I think this is about me.”

The Secret of Me, a film directed by Grace Hughes-Hallett, is about Jim. But it is about more than Jim. It is about why what happened to Jim happened. And about what that means for us now, when this is still going on.

It is also, unavoidably, about our present debates. At the start of the film Jim says, “I know what you are thinking: this is a transgender story. But it’s not.” Yet the parallels — and complexities — are there throughout.

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After that class, Jim went to the doctor’s surgery and requested his medical records. He read them in the car park. Almost the first thing he saw was that he was “XY”. He had male chromosomes. But there was more. His penis had been small. His genitals were “ambiguous”. “There was all this documentation about how my genital presentation needed to be altered.”

The surgeon got to work. Or as Jim puts it, “My genitals were crafted to have a very satisfying, pleasing vulva presentation, so that I could then be safely taken home by my parents.”

There was, we learn, a simple pragmatism to this. One of the extraordinary aspects of Jim’s tale — beyond the fact that we learn it is not so rare at all — is that Hughes-Hallett is able to get at it from all sides: she has interviews with Jim, but also archive interviews with his parents.

And incredibly, she interviews his surgeon, who explains what he did that day. “In 1976 the medical thought was these patients need to be surgically constructed,” Richard Carter says. “It was so much easier to make it look more like a clitoris, as opposed to trying to make a penis. So that’s what we did.”

James Rogan, Grace Hughes-Hallett, Jim Ambrose and Flora Stewart pose for a portrait.

The Secret of Me creators: producer James Rogan, director Grace Hughes-Hallett, star Jim Ambrose and producer Flora Stewart

ROBBY KLEIN/GETTY IMAGES; IMDB

Hughes-Hallett came upon this story thanks to her brother, a urology surgeon. “Four years ago he called me from a medical conference and said, ‘Doctors here are talking about all of these adults that are coming to urologists having had surgeries done on them as infants. They are begging for them to be undone.’ He said, ‘There’s something in this.’ I really didn’t understand what he was talking about.”

Depending on how expansively you define it, as many as 1 in 60 babies is born with a disorder (or difference) of sexual development (DSD), although the figure for children in which their genitals are hard to classify is many times lower. For example, Dsdfamilies, a UK charity, estimates that there are about 130 children diagnosed each year with DSD — about 1 in 4,000. Historically, and sometimes today, a decision was taken at birth to make their genitals accord more to one sex than another.

But what do genitals, or gender, matter? Maybe they don’t. In the 1960s and 1970s, amid sexual and social liberation, there came ideas of gender liberation. What if our idea of what it means, socially, to be a man or a woman is an imposition, a reflection of societal expectation? There was no doubt that a lot of it was. There is no evolved reason for girls to like pink, for instance.

John Money, a Johns Hopkins University psychologist, went further. What if, in nature v nurture, it was all nurture? What if we were a blank slate, and what we thought of as inherently “masculine” or “feminine” behaviour was nothing but a mirror of our prejudices?

“It is a characteristic of the human species that men and women have gender identity, that newborn babies don’t and that developing infants develop one,” Money said. “They develop it in much the same way that they develop their native language.”

He had the evidence to prove it too — a natural experiment that could almost have been designed. There were twin boys, Bruce and Brian, in the 1960s who, at the age of seven months, went for a circumcision. It was botched, and Bruce lost his penis.

Bo Laurent feeding her chickens.

The film features the American intersex activist Bo Laurent, better known by her pseudonym Cheryl Chase

Money advised the parents to raise him as a girl. And, according to Money’s research, it was an astonishing success. In papers Money wrote about the case, Brenda was interested in dresses and dolls and sugar and spice and all things nice. Brian was a normal boy, Brenda a normal girl. Her gender had been constructed, just like her genitals.

This evidence had coalesced just in time for Jim to be born. His doctors followed the Money protocol. Surgery at birth. Hormones at puberty. More surgery in late teens. Part of the Money protocol is that you don’t say why this is happening. Don’t tell the truth.

So Jim’s parents didn’t. He remembers a childhood that was never quite right. Tomboyish. “I consider myself lucky that I got a bicycle in the same year I got a Barbie,” he says. “One got far more use than the other.” He found a home in the football team, then found his teammates started getting earrings and boyfriends.

At the age of 12, he sat with his mother while she tearfully explained what came next. “She said, ‘Soon you’re going to have to take these pills that will help you grow and develop breasts and make you look like other girls.’ Finally, she said, ‘You’ll never be able to have children of your own.’”

Then, before college, came the surgery itself. They took part of his colon to construct a vagina. “Presto!” Jim says. “Between my legs there is a hole for my husband to have sex with.” Today, Jim no longer has his colon-vagina, nor his breasts. He has a beard and he takes testosterone — the testosterone that should have been made in the testes that were removed.

Brenda was not so lucky. Even while Money was writing papers about how feminine Brenda was, her mother was writing to Money about how tomboyish she was. When, decades later, Brenda was tracked down, she was living as a man called David. David later killed himself. Money never admitted the study had gone wrong.

Jim cannot forgive him for that. “He knew before my birth it had failed completely. Ego and reputation were more important than telling the truth and saving children like myself from mutilation and shame and brutal secrecy.”

His is, he is clear, not a transgender story. The intersex community is tired of being co-opted into a different debate. Indeed, they suffer by being co-opted. Testosterone, for him, is a medical necessity. Hughes-Hallett said Jim is worried that, because of restrictions on transgender medicine, he will struggle to access the hormone. “It isn’t an identity thing for him,” Hughes-Hallett says. “It’s a survival thing.”

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And yet, it will be impossible not to see the parallels. What moral do you take? This is a story about people convinced they are in the wrong body. It is about what happens when your idea of your gender doesn’t correspond to your sex. It is about people whose very existence appears to contradict the idea of a simple sexual binary.

It is also, though, about the primacy of biology. It is about what happens when ideology outpaces the evidence base. And it is about well meaning people who do things to children for what they consider the best reasons, who then find themselves accused of mutilation.

For Hughes-Hallett, there is a more pressing moral. When children are born with ambiguous genitals, surgery at birth is not banned, including in the UK. Intersex UK is one of several groups lobbying for an end to non-medically necessary surgery at birth. That’s why, she said, “We want to get this film in front of as many medical students as we can.

“More established doctors who’ve been doing these surgeries for decades don’t want to hear they’ve been doing something wrong. But medical students are really open to learning about a practice that might be in need of changing.”

The Secret of Me is being screened at Bertha DocHouse, London, Oct 22-23, Everyman at The Whiteley, London, Nov 12, and will be on Channel 4 in 2026