Former Hobsons Bay mayor Tony Briffa.
Given a choice between male and female on official documents, Tony Briffa ticks both boxes but prefers to tick neither. Briffa also prefers not be referred to as "he" or "she".
''I would honestly feel like I was lying if I filled out a document and I put one or the other,'' says Briffa, a former mayor of Hobson's Bay who has tried living as both a female and a male.
Christy North, now 34, was diagnosed with complete androgen insensitivity syndrome when she was aged two.
Briffa was born with partial androgen insensitivity syndrome, one of more than 30 ''intersex'' conditions. The term refers to more than 30 different conditions characterised by having biological attributes of both sexes or attributes that are not wholly female or male. These may be chromosomal, hormonal or physical variations including ambiguous genitals.
''I was born both and I feel both,'' Briffa says. ''And I fiercely want to be recognised in the gender I was born, which is both.''
For the first six weeks of our lives we are arguably all intersex. Humans do not develop sexually distinct features until a series of genetic and hormonal catalysts begin their work in the seventh week of life in the womb. Individuals who do not travel the conventional biological path to maleness or femaleness develop intersex conditions, also known by doctors as disorders of sex development or DSD.
Sometimes known as hermaphrodites or androgynes, these permutations of male and female have been known to exist; people recognised that sexuality is more like a spectrum, or ''an overlapping pair of bell curves'', than a binary set of two genders.
Medical studies estimate between one in 250 babies are born with one of the milder intersex conditions and one in 4500 births for rarer conditions. This means intersex conditions are more common than Down syndrome. International studies show over 1 per cent of all babies have some kind of intersex condition.
''Society is happy with the idea that this kind of variability around sex is incredibly rare,'' says Gina Wilson, president of advocacy group Organisation Intersex International. ''We're saying it's more common than being redhead.''
Over the past century differences of sex development were hidden from the public and hospitals hid diagnoses from parents. Surgeons performed genital surgery entailing sterilisation and lifelong hormone treatment to assign infants one gender or the other, often with the consent of poorly informed parents. Sometimes the surgeons got the gender assignment wrong.
The use of surgery to change the sexual anatomy of children was promoted during the 1950s and 1960s by the controversial New Zealand-born sexologist and paediatrician, Professor John Money.
Money had his own - now disputed - theories about how sexual identity developed.
Based at John Hopkins University in Baltimore, he argued that social and environmental cues interacted with a child's genes and hormones to shape whether the person identified as male or female. He said early assignment of gender with medical reinforcement would help a child grow up happily in one gender.
Medical diagnoses and treatments have improved dramatically in Australia in the past 20 years.
These days fewer gender assignment or genital enhancement operations are done on children than 10 years ago.
The Royal Children's Hospital Melbourne currently performs one or two gonadectomies a year on infants with undescended testes. According to medical studies, in certain cases undescended testes have a 50 per cent chance of becoming cancerous, although some intersex groups point to studies that show lower risk and dissatisfaction with surgery.
The hospital also performs 10 to 15 genital reconstruction operations a year often on girls under the age of two. Genital surgery is conducted mostly on infants with female chromosomes and congenital adrenal hyperplasia, a condition that causes some girls to have more masculine-looking genitals. Surgery is conducted on female infants to open or enlarge vaginal openings or to reduce or reshape clitorises.
Associate Professor Sonia Grover, director of the department of gynaecology at the Royal Children's Hospital, says studies show girls with CAH would identify as females and want to have periods and sex later in life and that surgery done early produced good results. All infant surgery is conducted with the informed consent of parents.
''While we have the data to say they are going to end up identifying as females … and we have evidence that surgical outcomes are good, and sensory outcomes and sexual function are good, where's the pressure to change the practice?'' Grover says.
She says genital surgery can be compared to widely accepted cosmetic surgery to correct such things as a cleft lip and palate.
But when it comes to surgery older people with intersex conditions often suffered because of social and medical attitudes of the time.
''Trace'' was born in rural Victoria with Klinefelter syndrome (which gave her one extra X chromosome than the usual male) and non-conforming genitalia. Like other older intersex people, her early medical records have gone missing, but four operations as a child left her without any genitalia.
''It was never explained to my mother. She was told I had a condition and that I would never have a child and it would be best for me to have operations 'to clean up downstairs','' Trace says.
Trace was raised as a boy but her father, a Jehovah's Witness, physically abused her. She was eventually made a ward of the state but placed in a girls' home while she went to school as a boy. She refused to attend sports classes, preferring to be punished than having to undress in front of others in changing rooms.
She was placed on male hormones but later began to question her gender and stopped taking the hormones. In her 20s she became confused about her gender identity and eventually decided to adopt a female identity and name.
''If there was choice in life I certainly would have lived androgynously but society was so gender-driven in early days.''
Trace, now a successful business person, counts herself lucky because ''many older intersex people don't manage to fight off poverty and depression and some take their own lives''.
Every intersex condition has different physical manifestations and requires different management. Women with complete androgen insensitive syndrome (CAIS) are often tall and striking looking with slightly masculine or angular features and ageless skin. Some well-known actresses, models and athletes are known to have the condition.
Christy North, now 34, was diagnosed with CAIS when she was two and had internal, ''non-functioning'' testes surgically removed. At 12, she found out she wouldn't menstruate or be able to have children. She was also put on a lifelong oestrogen replacement course.
Hospitals no longer remove the testes of women with CAIS but North is not unhappy that hers were.
''I am more than happy to be female. I don't have a choice. I was born a female. I am XY. But I can't become male. I have female parts. Just not the internal makings of a female.
''In 20 years they will know what happens when you take HRT for 50 years. We also don't know what would happen if I stopped taking it. I just think what I do now could help those in the future. I don't want to see myself as a guinea pig, but I guess I can be.''
Parents face extremely difficult decisions about what treatments they allow their child to have soon after being told their baby has an intersex condition.
Andie Hider, vice-president and medical liaison representative for the Androgen Insensitivity Support Group of Australia knows a couple ''torn apart by grief because of a wrong decision [about gender] made when the child was young''.
Michelle Hoare, president of the Congenital Adrenal Hyperplasia Support Group of Australia, says: ''You don't want your child to look different. That's one of parents' main concerns.''
She poses the question: ''Would you terminate a child that has abnormal genitals?''
The Australian president of Organisation Intersex International, Gina Wilson, is concerned that prenatal screening and ultrasounds may be leading to an increasing number of terminations of foetuses with intersex conditions.
Anne, a parents' representative for AISSGA, whose daughter has CAIS, says ''You think it is the end of the world when you first find out and then you find out they can still lead a happy fulfilling life regardless.''
Indeed, while there are people with intersex conditions on company boards, winning Olympic medals and contributing at every level of society, there is still a stigma surrounding the condition and most intersex prefer not to disclose that they have it.
Professor Grover confirms that stigmatisation is still a big problem.
''We would never have one of our patients [with a disorder of sex development] as the face of a Good Friday appeal because of the stigma associated with the diagnosis,'' she says.
''That's what does the damage. Shame and secrecy,'' says Mani Mitchell, president of OII New Zealand.
''If we are going to change anything it is to help parents be comfortable with a child who is different. Helping parents find a different language to talk to their kids.''
Mitchell says society advocates acceptance of racial difference but has trouble accepting sexual difference. ''We don't deal with racism by turning everybody brown.''
Advocacy groups believe the continuing use of the medical term ''disorder of sex development'' perpetuates stigma and helps persuade parents their child has a problem that needs to be fixed.
The federal government is taking steps to help reduce this stigma. From July 1, the new federal Guidelines on the Recognition of Sex and Gender will allow Australians to tick a third box, the ''X'' box, denoting ''Indeterminate/Intersex/Unspecified'' on all government documents, including passports.
Also The Sex Discrimination Amendment (Sexual Orientation, Gender Identity and Intersex Status) Bill 2013, which is expected to be passed by the Senate this week, will give intersex people legal protection against discrimination for the first time in Australia.
But Andie Hider says governments need to go further. ''Do we really need to have male or female on a driver's licence or a birth certificate?''
Indeed, some intersex people see debates about subjects such as different and same-sex marriage as absurd. ''Every relationship I have is going to be part heterosexual and part same-sex.'' Briffa jokes: ''Maybe I can marry myself.''
Andrew Bock is a Melbourne journalist.