It's not easy to summarise American filmmaker Kimberly Reed's remarkable new documentary, Prodigal Sons, but she has her own way of introducing it to audiences.
You know how it is when you grow up, leave home, and change a lot? Then you return home to find that your parents and family don't get you any more? That's what Prodigal Sons, essentially, is all about."
Not quite. At the start of the film, 42-year-old Kimberly is making her way back to her hometown of Helena, Montana, for her high-school reunion. The twist is that in high school, Kimberly was named Paul McKerrow and was the star quarterback on the football team.
Already the toast of several film festivals around the world, Prodigal Sons isn't just about transsexual Kimberly's first journey home since she changed genders. Her troubled, adopted older brother Marc also has his own identity struggle, one that culminates in a jaw-dropping revelation in the film that's so bizarre and out-there that it could only be true.
Like many other transsexual people, Kimberly says that she always felt uncomfortable in her body growing up, but that it was a slow realisation about what was really going on. "That was due to a lot of repression," she says.
"I think that's very common. It was a very lonely, isolating experience. I never confided in anyone. I was always a bit of a loner, and stuck in my own head. I was very quiet, but I was still quite popular in high school. I was class president and valedictorian, and I played football. I was pretty good too.
"I had girlfriends throughout my teens. I guess I was trying to find things that would 'fix' me and that meant doing the things I was expected to do growing up."
It was only when Kimberly left school, and went to study in San Francisco that she decided to change gender from male to female.
'I had a very slow transition," she explains. "I know a lot of people who do it overnight -- literally. For me, I was slowly transitioning as I was working through school and starting off in my career. It took a good few years; the standard practice is to go through a lot of therapy and counselling as you're going through the process.
"My family knew about it to varying degrees at different times. My younger brother Todd is gay and also lived in the Bay area in San Francisco, so he was the first I told, along with my mom. My older brother Marc was the only one who wasn't in on everything.
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"My father died in 2003, but he had seen me before that. I was nervous about it, obviously, but I wasn't surprised that my parents proved to be so supportive."
Kimberly argues that there is an over-emphasis on the surgical aspect of changing genders, whereas the biggest transition really happens after the operation. "How you're accepted as female in society after the surgery is what's most important," she says.
"After I transitioned I was a bit uncomfortable about it all. When you change your sex, there's a tremendous pressure to bury your past and to 'disappear'. That's what I did. I gave up being a filmmaker, and worked in publishing instead for many years.
"When I started making this film, I found my brother Marc was the only one who wouldn't let me get away with forgetting my male past. He forced me to reclaim it."
Kimberly says she retained a "healthy scepticism" all the way through her process of changing sex.
"I think anyone who transitions often wonders, 'Well, I started off in the wrong body, am I going to end up in the right one?' That scepticism is why it's important to take the whole process step by step, rather than doing it radically overnight."
Living her new life as a woman, Kimberly admits that she found conducting relationships difficult at first. "I guess I just dreaded the conversation," she says. "But I really found that the more at peace I was with it, the easier it was for other people to accept. I've now been with my partner, Claire Jones, for the past nine years."