A person’s biological sex seems simple but is deceptively complex. It appears to be binary: An XX chromosomal pair is female, and an XY chromosomal pair is male. Doctors look at a newborn’s genitalia, pronounce the baby a boy or a girl, and the birth certificate reflects that sex assignment.
...Yet the reality is that today in the United States alone there are approximately one million people who — from the moment of birth — cannot clearly be defined as either male or female.
Many people share the ubiquitous notion that biological sex falls into two, mutually exclusive categories. In 2009 my perspective changed when I read an article written by a woman who learned shortly after marriage that she and her husband couldn’t have biological children because she had an XY chromosomal pairing. While she looked like a woman, and she and her parents had always believed she was female, from a genetic standpoint she was a man. The article was published the year after California passed Prop 8, a version of DOMA.
As Prop 8 wound its way through the courts, I thought about that article often. The legal briefs that were filed in both state and federal courts largely focused on equal protection for the LGBT community. Lawyers debated due process and the separation of church and state with a sprinkling of right-to-privacy arguments. But I wondered how that woman and her husband fit into the analysis.
I was curious whether her situation was an obscure medical anomaly that was statistically and legally irrelevant. It wasn’t. A regularly cited 1991 study of nearly 35,000 newborn children found that 1 in 426 did not have strictly XX or XY chromosomes. In addition, the World Health Organization reports that 1 in every 2,000 births worldwide are visibly intersex, because the child’s genitals are either incomplete or ambiguous, which equates to five newborn Americans a day. This represents a sizable U.S. population that cannot be ignored by the law.