It's the first question any parent asks after the birth of their child: is it a girl or a boy? In very rare cases, the midwife has to say honestly: "I don't know."
There are babies born who, left to grow up without medical intervention, will be both and neither. They have been called hermaphrodites, pseudohermaphrodites and intersex children but doctors now prefer to speak of sex development disorders, because a disorder can often be put right. These children do not have to live their lives in a state of sexual ambiguity. If the condition is identified early enough, they can be given help to grow up with a specifically male or female body.
In the past such babies were sometimes subjected to surgery verging on the brutal. Others will never have been detected or will have chosen to go through life without seeking medical help with little chance of ever having a child themselves. Some, particularly those called "over-virilised" women, may have sporting potential because of their unusual strength. At the Atlanta Olympics in 1996 eight female athletes failed sex tests but were cleared on appeal and seven of them were found to have physically developed as neither fully female nor male.
The International Association of Athletics Federations is going to muster a host of experts to decide whether Caster Semenya is a man or a woman. According to Professor Wiebke Arlt, professor of medicine at Birmingham University, the question of which is the most appropriate sex when a child is born is a relatively straightforward one.
All of us have 46 pairs of chromosomes, plus the pair which, in most cases, decides our sex. Either we have what they call 46XX and are female or 46XY and are male. But sometimes there is a mismatch between the body's male and female hormones and those key chromosomes. Sometimes that can be corrected so that the chromosomes decide the sex, but sometimes it cannot and the hormones have to prevail.
One of the more common disorders but which only occurs in one in 15,000 births, has made great beauties of women who technically were born male. (There has been unsubstantiated speculation that actors Marlene Dietrich and Greta Garbo had this disorder, although such rumours could easily be explained by people's discomfort with their androgynous appearance.) Their chromosomes are 46XY and they have male hormones, but those hormones cannot act because of a mutation in the protein to which they are supposed to bind. "They would look and behave like a girl," said Arlt. "Many models and film stars have this disorder. They are very tall and slender featured, very beautiful with peachy skin.
"They usually find out because their period doesn't start. They do not have a uterus: the vagina ends blind. They have testicles in the abdomen which must be removed or they can become cancerous.Apart from the fact that they can't bear children, they are completely female." Yet these women have XY chromosomes. If sex testing were limited to chromosomes, they would be declared male.
At the other end of the spectrum are those who are 46XX and should be female, but have too much action from male hormones, because of a deficiency of the stress hormone, cortisol. Somebody with this condition, called congenital adrenal hyperplasia, "may look on the outside like a boy," said Arlt, "but once a month they may have blood in their urine. "The genitalia doesn't need to be completely male, it can be somewhere in between. These days, doctors would do genital corrective surgery quite early on." Normally somebody with this condition would be assigned a female identity but Arlt has had such patients in her care who were raised as boys and are now middle-aged men with families. Hormones are key to sex, but levels vary from person to person. "There will always be women who are more muscular and have more male movement," said Arlt. It doesn't have to mean they are men.
