It s a boy. No, it s a girl. Wait a minute. Exactly what sex is it?
Parents and doctors in the United States ask those questions in about 1 in every 4,000 births each year. These kids are born with ambiguous genitals. Intersex babies, they have disorders of the sex organs or sex chromosomes that make it difficult to say whether they are male or female.
Laws and culture, however, encourage parents to make the call immediately. Birth certificates, for instance, are among many documents that require a declaration of male or female.
Social attitudes provide another nudge to declare gender. It s the first question that new parents get from family and friends. What do you say? What do you name the baby? How do you dress it?
Those are among the reasons parents usually make the decision, and sometimes even opt for sexual assignment surgery. When parents decide it s a girl, for instance, male-appearing anatomy can be surgically reduced in size, along with other changes to make the genitals appear more female.
New research discoveries, however, are raising questions about whether sex assignment surgery should be done on children who are not mature enough to help make the decision. It s one situation where scientific knowledge about what makes a male or a female is outdistancing social attitudes and the law.
The making of a male or female is not as simple as Biology 101. Mom s egg does contribute an X chromosome. Dad does determine the sex by contributing either an X or a Y. An XX fetus is genetically female, and an XY is a genetic male.
However, both fetuses still develop for a while with the same general-purpose reproductive tissue that eventually forms male or female genitals. A hormonal process causes the tissue to become male or female. If something disrupts that process, the fetus can end up with ambiguous genitals.
Scientists once thought that the hormonal process also made the brain masculine or feminine. New research, however, suggests that a separate process is involved. Studies with laboratory mice have found that male-female differences exist in the brain long before the hormonal process occurs. Dozens of genes already are working differently in male brains than female brains before it produces male or female genitals and reproductive organs.
The brain may be hard-wired at conception to be at least partly male or female, no matter how the genitals develop.
The discoveries show that scientists have yet to discover or understand parts of Nature s recipe for deciding whether it will be a girl or a boy.
More doctors are advising parents to delay decisions about sexual assignment surgery until the child is mature enough to have a say. Otherwise, children assigned one sex as babies may begin identifying themselves as the other a few years later.
The best way to decide the sex of an intersex child may be to let the child decide.