Intersex conditions occur in one out of every 2, 000 births in the United States, according to the Rohnert Park, California-based Intersex Society of North America.
Most groups campaigning for intersex people now advocate that doctors should not perform medically unnecessary genital surgeries on intersex babies to make them male or female.
It could invalidate some unions involving an intersex partner, but also allow a genetic male and female to marry even if they look as if they belong to the same sex.
People who are intersex could also have the condition and not be aware of it, as was the case of Indian athlete Santhi Soundarajan, who failed a gender test at the 2006 Asian games and was stripped of her medal.