JANINE COHEN: As many as 40,000 Australians don't have standard sex chromosomes. The scientific principle used for decades - that all girls had XX chromosomes and all boys, XY - isn't reliable.

Are we just on the cusp of learning what determines gender?

PROF. ANDREW SINCLAIR: We really are. I mean, we are just beginning to understand this, and I think the more we go into it, the more we understand how complex this whole situation is. As I said, it is a very complex network of genes that operate in space and time.

JANINE COHEN: Christie North has always felt female. But when she was 15 she found out she was born with male chromosomes and internal testes.

CHRISTIE NORTH: There was no mention during school, during human development, that there can be mix-ups with your chromosomes.

JANINE COHEN: The scientific world is on the verge of discovering what really determines gender and in many cases how little it has to do with our environment.

ANDIE HIDER: I just sort of grew up with scarring and things and thinking, "Well, okay, what was this for? Why did I have this?" But I'm being told these particular things, I'm being told that, yes, you know, for this stage in my life I'm a boy, therefore I must be one -

JANINE COHEN: Why did they make you a boy?

ANDIE HIDER: Um, I have no idea. I have absolutely no idea why they did it.

JANINE COHEN: Australian law, too, is grappling with the latest science on what it means to be male or female. The federal government tried to prove this person was a woman.

"KEVIN": The last thing you want to be doing is trying to prove that you are the person you are to someone that doesn't know you, someone that has no idea about your life, never interacts with you at all, has never met you.

"JENNIFER": I know what a man is, and I know what a husband is, and I know what a father is; and he's all of those things.

JANINE COHEN: Tonight on Four Corners, new and challenging science on the question of gender. What makes a boy and what makes a girl?

If we relied on the common scientific definition of a male - that being someone with XY chromosomes - then Christie North would be a man. As an unborn baby she was unable to process male hormones, so she developed instead into a female. The Melbourne woman has an intersex condition called Complete Androgen Insensitivity Syndrome. This is one of more than a dozen different types of intersex conditions affecting thousands of Australians.

So there was nothing that made you any different from any of the other girls?

CHRISTIE NORTH: No, not at all. Even when I told my friends - I only told a few friends, but they had no idea.

PROF. GARRY WARNE: My way of thinking is that she was always intended to be a girl but she just got there by a different path. That, I think, is a fundamentally different way of thinking. Instead of the negative way which says, "This is a boy who didn't make it," This is a girl who did make it and was meant to make it this way, but life was just meant to be also a little different.

JANINE COHEN: Many of these XY women are tall and beautiful. There are rumours that some actors and models have the condition. It often produces women with little body hair and clear skin.

CHRISTIE NORTH: It's something that I have. It's not something that I think about on a daily basis. I think about it occasionally and I mention it - like if I mention it to friends or a prospective boyfriend or something like that, that's the only time it ever gets mentioned or brought up.

JANINE COHEN: What has it meant for Christie to have XY chromosomes?

LIZ NORTH: Oh, I think she's happy. I think she's happy. I don't think it's worried her at all. She's never really complained or - she's just a normal - oh, well, a normal girl, you know, into the hair, coloured hair, make-up, you name it. She's into the latest fashions.

JANINE COHEN: When Christie North was two years old, she went into hospital for a hernia operation. Internal testes were discovered, and Christie was later diagnosed with Androgen Insensitivity Syndrome.

PROF. GARRY WARNE: She was born with testes that are capable of making the male sex hormone, testosterone. Her body is unable to respond, in any way, to that hormone because the receptors in every cell in the body for testosterone are absent, and the reason for that is a genetic alteration.

CHRISTIE NORTH: When I was in grade six, Professor Warne, or Dr Warne then, sat me down with my parents and my sister, and we discussed that I was unable to have kids and menstruate, and that was pretty much all that was said then.

JANINE COHEN: It wasn't until Christie North was 15 that she was told that she had male chromosomes and was born with testes.

Would it have been in any way easier for you if you had've been told everything at the beginning?

CHRISTIE NORTH: Well, yeah. Yeah, it would've. Sort of growing up thinking that you had a hysterectomy or something like that when you were younger, it's not the case when you find out later on. So it would have been a lot easier if you'd knew straight away.

JANINE COHEN: So you actually didn't know why you were infertile?

CHRISTIE NORTH: No, no.

JANINE COHEN: Every year, Christie North receives an implant of the female hormone oestrogen to help feminise her body.

LIZ NORTH: There's so many people with the same problem. There's more than what you think there is. You know, when you knew people that didn't have children you think, "Oh, why didn't they have children?" So now we know why a lot of older people didn't have children. It's because they had this problem and it was never spoken about.

JANINE COHEN: Like Christie, tens of thousands of Australians don't have standard sex chromosomes. As well as girls with XY chromosomes, one in 500 boys are born with a double XX as well as a Y. Most have standard genitalia and are unaware of their chromosomal make-up until they try to father children and discover they're infertile.

So what does a situation like yours, having XY chromosomes, say about the gender spectrum?

CHRISTIE NORTH: Well, it's never all one or the other. It's - one in 500 people has a chromosome variation of some sort. So it's not uncommon.

JANINE COHEN: Most scientists believe we're just on the verge of learning what makes us male and female, and they believe one way to better understand this is through the study of those on the gender extremes.

PROF. ANDREW SINCLAIR: I think throughout history humans have been really interested in what makes us male or female, and underlying that is whether or not a testis or an ovary develops in the embryo.

JANINE COHEN: Until the 1990s, gender was thought to be largely about chromosomes. But this principle was challenged when a scientific breakthrough was made during the study of people with intersex conditions. A new gene and its impact on the development of male genitalia was discovered. A team of scientists, including Associate Professor Andrew Sinclair, discovered SRY, the gene needed to start the process of 'maleness'.

PROF. ANDREW SINCLAIR: The rationale for finding that gene was that we could unravel the whole process and build - understand how you build something as complex as a testis, and by knowing all the different component parts - a little bit like putting a car together - if you know all the bits, when something goes wrong you can pinpoint that and correct that if need be.

JANINE COHEN: It's recently been discovered that the SRY gene is also present in the male brain region of the hypothalamus, the same area where gender brain identity is developed.

ASSOC. PROF. VINCE HARLEY: We've had some success in understanding SRY and how it makes a testis. We're now trying to look at what SRY might be doing in the brain. There is some evidence from our studies that there are genes on the Y chromosome, which males have and females don't, that make at least rats more aggressive; and so it could be that there are male-specific behaviours that are carried by genes on the Y chromosome, such as SRY.

JANINE COHEN: Associate Professor Vincent Harley is now looking at a further 54 genes that have been discovered since SRY. These genes in the embryo are turned on differently in male and female brains, even before the organs that secrete hormones have formed. They may help scientists to explain why some people identify as one gender or the other, independently of chromosomes.

ASSOC. PROF. VINCE HARLEY: I think we're starting to understand how the brain is hard-wired differently between males and females.

PROF. ANDREW SINCLAIR: Our gender - how we see ourselves - is determined by our brains as much as anything else. So it's quite likely, one could imagine, that there'll be receptors in the brain which will respond to some of those hormones. So, if the gene or those receptors in the brain are not functioning and are not going to receive the male hormone, then that person may well have a feminine outlook. So the brain will influence gender as much as the gonads.

JANINE COHEN: Science is starting to redefine the gender debate. For years it was thought to be all about nurture - the way a child was raised. Feminist theory helped the idea along. Women limited themselves because they had been stereotyped and socialised that way.

ARCHIVE CHEQUERBOARD PROGRAM: It's a reality of twisted and thwarted people, people who are twisted and thwarted 'cause they're pushed into roles. Girls train themselves for their future. They take their dolls to the park.

DR LOUISE NEWMAN: Most of the theories of the time spoke about socialisation, spoke about the way parents train us into particular gender roles, and that was the prevailing model.

JANINE COHEN: In the '60s and '70s, doctors believed the power of nurture was so strong it could be applied to children where their sex was ambiguous. The practice was to assign a baby who often had both male and female genitalia a gender. The child would then undergo genital surgery and be raised in its assigned sex. The theory was the child would grow up happy and well adjusted. This philosophy was based on the work of a famous New Zealand psychiatrist, John Money.

ARCHIVE JOHN MONEY: When all of the problems and issues are cleared away early, one ordinarily expects that person to grow up, as I say sometimes for the sake of remembering it, in the psychological sex that agrees with the haircut.

ANNE HIDER: Unfortunately, he was very powerful and influential at the time and people took this theory as gospel.

JANINE COHEN: And what do you think of that theory now?

ANDIE HIDER: Well, I think if - a total reliance on nurture as far as sort of determining sex is complete rubbish. I think it just doesn't happen.

JANINE COHEN: Andie Hider is an example of the failure of John Money's nurture theory. She was born with ambiguous, or atypical, genitalia. Doctors didn't know what sex she was, so they took a punt and decided she'd be a boy.

ANNE HIDER: I guess we'd always been brought up in that generation to think that doctors were somewhat god-like. If you were told something, you believed it.

JANINE COHEN: Andrew Hider was a quiet, gentle little boy who always felt not quite right about his place in the world and didn't know why.

ANNE HIDER: He was certainly not a typical boy, not out kicking footballs and rough-housing. He was great at fiddling around making things, creating things. Very good with his hands always.

STEVE HIDER: Andie was never really terribly male or female, always slightly ambiguous. I guess looking back, I think Andie probably had a really difficult childhood.

JANINE COHEN: Andie Hider did a lot of the things that men do. She was into cars and mechanics. But, despite the masculine pursuits, people often mistook Andie for female. As a man, she started to question her gender.

ANDIE HIDER: I sort of thought, "Well, if I'm not male, then I must be something else," and the only other thing is female. So, for me, that was sort of the thing that made me realise, "Well, that's probably who I am."

JANINE COHEN: Andie Hider decided to do something about it. She applied for her medical records under the Freedom of Information Act. What she found shocked her. She was born with a rare but extreme intersex condition - Partial Androgen Insensitivity Syndrome. Andie Hider has male chromosomes but her body couldn't process enough masculine hormones, leaving her with many feminine attributes and ambiguous or atypical genitalia.

ANDIE HIDER: They obviously knew at the time what they were dealing with, but they just didn't tell my parents because it wasn't the culture to do so.

JANINE COHEN: Your parents had no idea?

ANDIE HIDER: No.

ANNE HIDER: I was outraged, I suppose, that in comparatively modern times anybody would make decisions about my child and, you know, her future without even telling me about it.

ANDIE HIDER: It would have been after I got my medical records, when I was about 30 years old, and went and told my mother.

ANNE HIDER: I know now that this was accepted practice that you don't tell people about this. It's, you know, something that must be kept quiet and out of sight and out of mind, but -

JANINE COHEN: So Andie's case wasn't a one-off?

ANNE HIDER: Oh, no. No, no.

JANINE COHEN: Andie Hider, a Federal Police officer, turned her anger into action. In her spare time she became an advocate for people with intersex conditions. Andie says the culture has been not to tell parents and particularly children of their conditions. She wants that changed and is calling for full medical disclosure. Andie Hider claims no amount of nurture will make someone a boy or a girl if they aren't one.

ANDIE HIDER: What I have an issue with now is the fact that the medical profession should have learned from stories like mine and learned from stories of other people and said, "Well, hang on, this isn't necessarily working, and there are options. There are other ways of treating this."

JANINE COHEN: And the medical profession haven't learnt?

ANDIE HIDER: I don't think they have, to be perfectly honest.

STEVE HIDER: I think Andie's life would have been a lot easier if she had known from the outset that, "You have a choice here", you know, "You are this type of person - not male, not female. You find out for yourself, rather than having something imposed on you that may not be the right thing."

JANINE COHEN: Professor Garry Warne is an endocrinologist who's been working with intersex children for almost 30 years.

PROF. GARRY WARNE: The medical profession thought they were in a privileged position of having the information and that the patients didn't need to be bothered by some of those painful facts.

ANDIE HIDER: He did actually start the sort of movement to tell the truth. A lot of doctors said, "No, you can't do that," You know, "What gives you the right to turn around and ruin these people's lives?" And, as he said, "Well, it's not ruining their lives," and he was quite right.

JANINE COHEN: In 2002, Garry Warne was made an honorary life member of the Androgen Insensitivity Support Group for his efforts to have intersex conditions disclosed. But he is a controversial figure. Like John Money before him, he still believes in surgically assigning a gender to babies with ambiguous or atypical genitalia. He believes failure to do this could damage the child.

PROF. GARRY WARNE: I think that it exposes the child to the possibility of ridicule and embarrassment. It's something that would make them feel very different from other children.

ANDIE HIDER: Now it's just ludicrous to turn around and say, "Well, let's try and alleviate some social embarrassment by surgically altering a child at that stage of their life."

JANINE COHEN: Many doctors and advocates believe it's wrong to surgically change genitalia until a child can have its say. But Professor Warne says his policy, when in doubt, is to make a child a boy. It provides more choice.

PROF. GARRY WARNE: It gives the person the greatest option when they grow up. They can easily reverse that and go back to female if they wish, but it's very hard to go the other way. So preserving options I think is what it's all about.

DR FINTAN HARTE: It's a very difficult clinical situation to be faced with. It's a very difficult assessment to make, and, as I said, the current paradigm would be to wait and see as much as possible, whereas the old paradigm would have been to intervene, surgically re-assign and to raise the child unambiguously.

JANINE COHEN: Some international studies challenge Professor Warne's view. In the US, 94 people with an intersex condition who had atypical genitalia were surveyed. More than half were unhappy with the sex they'd been assigned. Despite being raised as girls and having genital surgery, they became boys.

PROF. GARRY WARNE: It's a hot point. But we've also recently completed our long-term follow-up study at this hospital, and we got it right 96 per cent of the time. In our series, there were only two out of 50 who wanted to be the other sex.

JANINE COHEN: So what is the AIS Support Group going on about when they say how badly they've been treated by doctors and how unhappy people are with surgery? Where are they coming from?

PROF. GARRY WARNE: Well, I think that they're, unfortunately, a group of people who have had bad experiences and who feel empowered by belonging to a group and making their presence known.

JANINE COHEN: Why doesn't their bad experiences, then, correlate with your study?

PROF. GARRY WARNE: I think that - because the people that have had good experiences don't bother joining such groups.

ANDIE HIDER: We're not a group of malcontents. We're not a group of people who sort of get together and grind axes about doctors. There have been some good doctors. We give awards to doctors who do, you know, who are forward thinking, who do change things.

ASSOC. PROF. VINCE HARLEY: There is a nucleus in the hypothalamus that is differently sized in male and females.

JANINE COHEN: Andie Hider's story focuses attention on what can happen when chromosomes don't match gender identity. To better understand the biology of gender, scientists are researching another group on the gender extreme - transsexuals. They have the body to match their chromosomes but believe their brain has been hard-wired to go in the opposite direction.

ASSOC. PROF. VINCE HARLEY: People, since the dawn of humanity, have wondered why we feel the sex we feel, and I think in these - nature has kind of thrown up these variations, which are wonderful, and we should celebrate these variations in gender identity.

JANINE COHEN: Why should we celebrate them?

ASSOC. PROF. VINCE HARLEY: Because I think it tells us a lot about how we - how you and I - perceive ourselves as the sex we are.

Here in females it's about half the size.

JANINE COHEN: Transsexuals are particularly interesting to scientists who want to map out the pattern of human sexual development. They provide a unique sample that animal studies can't replicate. There is a small but growing body of evidence that transsexual brains are hard-wired in utero to be either male or female. Professor Harley hopes to prove in his study that brain sex is responsible for the transsexual condition.

ASSOC. PROF. VINCE HARLEY: I think there might be a public perception that, you know, transsexualism is a lifestyle choice, and I think to reaffirm a biological basis would be quite empowering for them.

JANINE COHEN: Professor Harley is researching a variance in the sequence of genes thought to be found in male-to-female transsexuals. He is studying the DNA of 50 people. His work may also help to explain why, as males or females, we behave the way we do.

ASSOC. PROF. VINCE HARLEY: Well, I think ultimately it would be great to find gender identity genes, and it might be through the studies of transsexuals that we'll get to those genes. In fact, I think it's the only way we're going to get to those genes.

JANINE COHEN: The theory of brain sex is not only challenging for science but also for the law. It was relied on for the first time in Australia in a landmark case in the Family Court. 'Kevin', a transsexual, wanted to marry his partner, 'Jennifer'. The federal Attorney-General's Department opposed the marriage, arguing that Kevin, in the eyes of the law, was female. To be a man, Kevin must have been born with male chromosomes, genitals and gonads. But, instead, he was born into the body of a female.

Why did you decide to get married?

"KEVIN": Well, I'm a bit of a traditionalist, first of all, and I really wanted to marry Jennifer, and - but the absolute crunch of the matter was to provide security for her and any children we chose to have later.

JANINE COHEN: The Family Court forbids the identification of parties to its proceedings. For the purpose of a court case, the couple were known as 'Kevin' and 'Jennifer'. This is the first time they've ever spoken publicly. They have been disguised.

"KEVIN": I remember going to bed night after night, you know, wishing that when I wake up that I'd be like all the other boys instead of being different.

JANINE COHEN: For as long as Kevin can remember he perceived himself to be male. When he was very young, his mother tried to persuade him he was a girl. She had her husband and child stand naked in front of each other.

"KEVIN": I just continued to say, "I'm a little boy." She kept saying, "You're not." And I think out of desperation she eventually made me stand in front of my father, who was naked, and said to me, "Look, you don't look like your father. You're not a boy," and I said, "But I am."

JANINE COHEN: Kevin was the oldest of four children. He had three sisters. His adolescence was traumatic. At school he was harassed for wearing boys' clothes. He had to learn how to fight to protect himself.

"KEVIN": So kids used to tease me and harass me constantly: "You're a girl, you're not a boy. Why do you dress like that? Why do you look like that? Why do you play soccer and football and cricket? Why can't you be like the rest of us?" And I'd just say, "I'm not like you. I'm not like you. I can't be you. I'm being myself."

JANINE COHEN: Then puberty kicked in. He started to develop breasts and menstruate.

"KEVIN": Oh, it was dreadful. It was absolutely dreadful. You know, it was like my worst nightmare. "How could this be happening? Something's wrong. You know, everyone kept telling me, 'You're a girl, you're a girl,' And now my body's telling me I'm a girl when I'm not." Like, "This is unbelievable. How could this be happening?"

JANINE COHEN: Ten years ago, at 29, Kevin heard for the first time about gender re-assignment surgery.

Where would you be now if you hadn't had surgery?

"KEVIN": Certainly not here. Certainly not here today, certainly not having the life - without a doubt, I would be dead. I was getting to the point where it was becoming more and more difficult to get up out of bed every day and put on this facade.

JANINE COHEN: What would you say to people who say, look, people like you should just get some therapy and be content in the body that you were born with?

"KEVIN": That's the biggest joke of all. They have no understanding of the concept of transsexualism. They have no understanding of what it's like to have a mind that's not in sync with your body. They have no idea at all. And I said, "You know, come and walk in my shoes for a day and see what it's like."

JANINE COHEN: Kevin started hormone treatment that led to hair growth on his face, chest and legs. Two years later, he had chest surgery followed by a hysterectomy.

And what about when you found out about Kevin's history? Did that make any difference to you at all?

"JENNIFER": No, except to say that it probably made me admire him more, certainly not less, because I could see what a huge journey he'd been on.

"KEVIN": I told her on our second date, and she was just incredible, supportive, understanding, caring and - well, history tells us she chose to come along on the journey because of me, who I am, not about my gender.

"JENNIFER": I had never had any sense of him other than that he was completely male. His story about his transsexualism made no difference.

JANINE COHEN: Jennifer and Kevin started living together and not long after decided they wanted to start a family. Because Kevin was an infertile male, the couple applied to join an IVF program and use donor sperm.

"JENNIFER": I do think it was significant that it was a public hospital clinic which accepted us onto their fertility program. We were the first such couple that they had accepted onto their program ever, and so they needed to discuss the ethics of it.

I think the green ones should be in the middle because they're longer.

JANINE COHEN: After Jennifer conceived with their first child, the couple decided they should marry. Jennifer wrote to the federal Attorney-General asking if that was possible.

"JENNIFER": We wrote more letters explaining thoroughly all about it, the fact that my husband did have - had undergone the process of transition. He'd taken all of the available medical steps. He'd made all of the social adjustments. He'd made the other legal changes in terms of documentation. He had a male birth certificate, a male passport et cetera, and everybody whose path he crossed regarded him as male, from the people closest to him, such as his partner, you know, I might say, our extended family, the people he worked with and anybody that passed him in the street, you know.

CHILD: Go and get it.

JANINE COHEN: Jennifer and Kevin received an email back from an officer in the federal Attorney-General's Department. It warned, if they went ahead and got married, Kevin was liable for a penalty of up to two years jail. The public servant also predicted, if the couple took it to court, they would lose; and she suggested the law perhaps would change one day but not in her working life. She concluded with this: "Believe me, as a married mother of four, marriage is not all it's cracked up to be."

"JENNIFER": I felt very shocked when I read that. I was actually physically shaking when I read it. The woman that wrote the letter, who was in quite a responsible position in the department answering matters of family law and so on, just made no attempt to veil her personal bias.

JANINE COHEN: So this public servant offered a whole lot of personal comments?

"KEVIN": Oh, definitely, of which I found extremely offensive, to me as an individual, to Jennifer and myself as a couple. It was just outrageous.

JANINE COHEN: The couple decided to marry, despite the email, preferring instead to have the validity of their marriage tested in the Family Court. They hired lawyer Rachael Wallbank, herself a transsexual and expert on the condition. Rachael Wallbank decided to fight the case against the Attorney-General's Department on the basis of science.

RACHAEL WALLBANK: We were able to take the court through a journey, really, a scientific journey that firstly dealt with the kind of diversity in human sexual formation, arising from chromosomal diversity as well as bodily formation diversity, to the point where we could deal with evidence concerning brain sex differentiation in the human being.

JANINE COHEN: The court was presented with several scientific studies suggesting a biological basis to transsexualism. A Dutch study looking at the hypothalamus of six male-to-female transsexuals found they had similar features to female brains. They examined the part of the brain essential for sexual behaviour and found it was the same size in female transsexuals as it was in other women. In men, this region of the brain, known as the bed nucleus of the stria terminalis, is much larger. The study suggested that gender identity develops as a result of an interaction between the developing brain and sex hormones. Other studies supported this theory.

JUSTICE RICHARD CHISHOLM: In view of all the evidence that I had, there's just no reason to see how it could possibly have been nurture. The things that characterise transsexuals are as much biological as mental, and that's terribly important for the law. So the point I was trying to make in the judgment is that the brain sex theory, the biological-based theory, doesn't seem to have any competitors in terms of explanation. Nobody else is saying, "Oh, there's this other plausible explanation."

JANINE COHEN: In his judgment, Justice Chisholm said, "It would be wrong to suggest that a person's sex depends on any single factor, such as chromosomes or genitalia." "Equally", he said, "It would be wrong to say it can be determined solely by a person's psychological state or their brain sex."

JUSTICE RICHARD CHISHOLM: It's not a preference but it's a sense of who they are that for them seems to be so fundamental that it's not an opinion and that it couldn't be changed. It's just an absolute sense, like a sense perhaps that life's worth living or that one is alive or that you're sitting on a chair.

JANINE COHEN: Justice Chisholm also considered Kevin's social standing, the fact he'd had gender surgery and his success in being treated as an infertile man in a Sydney hospital's IVF program. Justice Chisholm determined that Kevin at the time of his marriage was a man and therefore the marriage was legal. He said in his judgment ...

JUSTICE RICHARD CHISHOLM: "It's difficult to imagine how there could be a stronger case on the facts for a person with female chromosomes born with female genitalia and chromosomes to be treated as a man. I refer to the extensive evidence relating to his self-perception, appearance, medical history and functioning in society."

JANINE COHEN: The Attorney-General's Department appealed Justice Chisholm's decision, and the case went to the full bench of the Family Court. It also decided in Kevin's favour. Kevin and Jennifer are now happily married, living with their two children in suburban Sydney.

"KEVIN": That's all we want, is to blend in and get on with our lives. We don't want to go out saying, "Hey, we're different. Hey, look at us. Hey, treat us with a special kind of" - I don't know what. We're just like everyone else. We just - we work. We pay our taxes. We care for our family. What more do you want?

JANINE COHEN: Far more controversial than adults changing gender is the issue of adolescents wanting to. Children seeking medical treatment must go through the Family Court. This follows a controversial case last year in Melbourne where Alex, a 13-year-old born into a girl's body, wanted to become a boy.

NEWSREADER: A teenage girl has become the first child in Australia to be given legal approval for a sex change on psychiatric grounds. The teenager, known only as 'Alex', will be allowed to start irreversible hormone treatment when she turns 16. But the court decision has divided medical authorities.

DR FINTAN HARTE: Alex was a very distressed adolescent who was extremely depressed because of his gender dysphoria, was quite suicidal, and certainly evidence suggests that he is much happier now having commenced treatment.

JANINE COHEN: The court decided the teenager could take the chosen name of 'Alex' and should be referred to as a male. It also agreed to the contraceptive pill to suppress menstruation.

DR LOUISE NEWMAN: Essentially I think we saw a very conservative judgment. This was a complex issue. This is a young person already living in a male role. I think what was very positive about it is that it respected the young person's decision to do that and supported that choice which had already been made. In terms of biological interventions, it was a very conservative approach, using only reversible interventions.

JANINE COHEN: At 16, testosterone will be considered to begin his physical transition. The court found the teenager's desire to be male was most likely due to biology and psychosocial factors. The judge referred to the expert medical evidence in Kevin's case.

CRAIG ANDREWS: Nobody chooses to go through this route. It's not something you would choose for yourself or you'd wish on your worst enemy type of attitude. It's not a walk in the park, it's not simple or easy, and it involves a lot of medical intervention.

DR LOUISE NEWMAN: Tell me what the good things about being a girl are. What do you like about being a girl?

JANINE COHEN: Dr Louise Newman specialises in child and adolescent gender issues. She currently has four adolescents wanting treatment to change gender. To do so, they will have to get permission from the Family Court. A 13-year-old who says she is a girl born into a boy's body recently went before the Family Court in New South Wales seeking the first stage of treatment.

DR LOUISE NEWMAN: In this case we are seeking to use puberty-blocking hormones which will delay pubertal change in this young person, on the grounds that they'll be distressed by that and probably not able to tolerate that, and that it is very clear for them that those changes are not going to be acceptable.

JANINE COHEN: Lawyer Rachael Wallbank presented medical evidence in court that puberty-blockers were reversible and could save the child from self-harm or, worse, suicide. Not everyone agrees with the view that adolescents should receive puberty-blockers for this condition. Many religious organisations are opposed to any form of medical intervention, and some doctors question the long-term effects of puberty-blockers.

PROF. GARRY WARNE: I don't think we really know the long-term effects on bone density of missing out on a couple of years of the accumulation of bone density.

RACHAEL WALLBANK: All the medical evidence, all the lived experience of people with transsexualism, like myself, however, and all of the post-treatment studies of children indicate that the earlier the children with transsexualism receive this treatment the better their lives are, the happier they are and the more they can actually live out a useful and fulfilling life.

JANINE COHEN: What about the critics who say: Adolescence is a time of turmoil anyway, they could grow out of it, they could change their mind, they could in fact simply be gay? What do you say to those critics?

RACHAEL WALLBANK: The treatment of transsexualism in childhood is a very conservative process. Usually years go by with the child under the microscope before the child's even able to commence on the totally reversible stage one treatment. What I say to those people is, "Please keep an open mind here. It's not within your experience. Transsexualism is not within your experience. It's within mine. It's within the experience of these children. If they don't have the treatment, they're faced with years and years of agony."

JANINE COHEN: Professor Garry Warne recently returned from a London workshop looking at the medical management of transsexual children. Advocates argue that puberty-blockers must be given to a child by 12 or 13, before puberty arrives. But Professor Warne and some other doctors believe they shouldn't be administered to any child under the age of 16.

PROF. GARRY WARNE: They're worried about making the wrong decision, and they're worried about it coming back to bite them later on.

JANINE COHEN: And can that happen?

PROF. GARRY WARNE: It has happened.

JANINE COHEN: At what age should a young person be able to take things like hormones, for example?

CRAIG ANDREWS: It's a dilemma because young people - it's a dilemma because you're wondering all the time whether the young person has a core gender of the sex they identify themselves to be or whether they've actually got enough life experience to make that judgment.

G'day.

JANINE COHEN: Craig Andrews runs a support group for female-to-male transsexuals. He has been concerned about the increasing number of teenage girls contacting his organisation wanting treatment because they think their lives would be better as men.

CRAIG ANDREWS: I think young people, for a whole range of reasons, can grab hold of answers that might not be answers.

JANINE COHEN: Three weeks ago, Rachael Wallbank's client received permission to have their 13-year-old child treated with puberty-blocking hormones. The lawyer will soon return to court seeking an order so the parents don't have to go through the Family Court to access further medical treatment for their transsexual child. The next stage would include oestrogen to feminise the teenager. Rachael Wallbank says, if successful, this would be a precedent-setting case, making it no longer mandatory for children to go before the Family Court for treatment.

RACHAEL WALLBANK: In my view, once a court hears more complete evidence about transsexualism, the kind of evidence that Justice Chisholm heard in Re Kevin, then the court will be more comfortable about allowing the treatment of transsexualism in childhood, to follow a medical course rather than imposing on the parents of these children the additional burden, financial and mental burden, of having to take the child through a legal process to enable that child to receive the treatment that the child needs.

JUSTICE RICHARD CHISHOLM: The question whether procedures relating to transsexualism require court approval I can well imagine might be controversial, and I suppose one might be more - the argument for having it approved by a court would be stronger in the case of irreversible steps, like surgery.

PROF. GARRY WARNE: We think that there must be some compromise that can be reached here whereby the court perhaps agrees to certain guidelines.

JANINE COHEN: As science discovers more about what makes a boy and what makes a girl, these difficult decisions may be made a little easier. But, for now, we are only just starting to understand how complex the biology is. It certainly isn't as simple as XX and XY.