When Harper Robertson opted to change sex and live as a man, his parents were shocked and confused. Now they welcome the transformation. Nick Duerden hears the family's story

Harper Robertson can vividly recall a conversation he had with his grandmother when he was just seven years old. Though still presenting – as the terminology has it – as a girl, with lustrous blonde hair and a fondness for dresses, his grandmother detected something deeper.

"Do you wish you were a boy?" she asked.

"Of course I do!" Harper responded.

It was a conviction that wouldn't go away, but rather increase throughout the agony of adolescence. At 14, he came out to his mother Kathleen Beller, but hesitantly, as if he weren't entirely sure.

"He then went through a tomboyish phase," says Beller, "but I didn't think anything of it; I had gone through a tomboyish phase. And then he got into bellydancing..."

The bellydancing didn't last, and Harper withdrew into deeper and deeper confusion.

"I started searching online," he says, "and came across a lot of YouTube blogs about people in transition. I didn't know I was transgender myself yet, but I did keep going back to those blogs, so something was clearly going on."

According to recent reports, there may be up to half a million people in the UK currently experiencing "disruptive gender variance", a somewhat clunking term afforded to those people who believe they were born into the wrong body. Of those half a million, a comparatively small number actually go through with transitioning: just 7,500.

"I personally never identified with either gender role," Harper says. "Pushing girls towards clothes and make-up always seemed silly to me, but then so did pushing boys towards sport and aggression. I was in neither camp; instead, I was at the side of the playground, reading a book."

Harper grew up in San Francisco, the oldest of three children born to 1980s pop star Thomas Dolby and US actress Kathleen Beller. Living in one of the country's more permissive cities certainly lessened his sense of alienation, but only marginally. School, he says, was hell.

"But then this is a very difficult and painful thing to go through. There is a certain level of shame attached to it, and you can't help but fear for your future because all trans stories within the media tend to be terrible ones. It's always portrayed as a kind of death sentence: to your future career, your future happiness, and any chance of a personal relationship."

He opted out of school in his mid-teens, electing to continue his studies online. "I just felt increasingly alienated, and made a point of not speaking about it, because the more I said, the less I had in common with anyone."

Four years later, he had relocated with his family to the UK, and began living as a man the day he enrolled at university, to study architecture. Surgery and hormone treatment followed over the next 12 months.

There are a variety of surgeries one can have, he explains. "Top surgery on your chest, lower on your, you know, lower bits."

And which did he have?

He smiles patiently. "For general purposes, it is not a good idea to ask trans people that. I have had surgery, yes, but I won't specify what."

Harper is now 21, and male. His features are fresh-faced – one imagines he doesn't have to shave every day – and boyishly cute, and his voice has an either/or ambiguity about it. Is he happy with the results?

His cheeks redden, and he laughs. "Well, I always found having breasts a bit of a nuisance, so after surgery and hormone treatment – which lowers your voice, gives you facial hair, more muscle mass, and narrower hips – then, yes, it's been a pretty good deal."

To date, Harper says, his trans experience has run in stark contrast to the calamitous kind one normally reads about. Bad things have not happened to him, and the level of acceptance he has had – from friends and family, and his long-term partner Joe – has been unfailingly positive.

Nevertheless, it did take his parents some time to get used to it. "It was a lightning bolt," says Thomas Dolby. "I just didn't understand it, and I couldn't fully relate. Neither of us could."

At first, his parents wondered why Harper couldn't simply be gay and live androgynously, and contentedly, in San Francisco's gay district. Many do. And Kathleen Beller, especially, struggled with the idea of surgery. Having quit acting, she was working as a doula, helping new mothers with breastfeeding, "and I had to come home to the fact that Harper was about to have a bilateral mastectomy. That was hard".

Greater understanding came about largely through Harper himself, who educated them and encouraged them to seek counselling. "We had a lot of questions," says Dolby.

Questions satisfactorily answered, the couple gradually learned not to overreact. After all, Beller says, "Harper wasn't ill, he wasn't going to die." The biggest hurdle they had to overcome was accepting that where once they had two daughters and one son, they now have two sons and one daughter. They have been attentive over pronouns ever since. "I don't think we would have ever dared hope Harper would be as happy as he now is," says Beller. "It's such a relief."

As it is for Harper himself, too, although one senses he'd be even happier if he never had to discuss gender issues again.

"In many ways, the only story here is that I was once sad, and now I'm not," he says. "I always thought society ascribed too much importance on gender, so I know what I've done is a little ironic."

He has not changed sex simply to find his place within society, he insists, but rather, and solely, within himself.

"And it is nice to know that, by transitioning, I've already broken a huge social taboo. I'm at liberty now to break whatever rules I fancy."

For more information on families and gender dysphoria visit: mermaidsuk.org.uk