Insights: Going beyond X and Y; June 2007; Scientific American Magazine; by Sally Lehrman; 2 Page(s)

When Eric Vilain began his medical school rotation two decades ago, he was assigned to France's reference center for babies with ambiguous genitalia. He watched as doctors at the Paris hospital would check an infant's endowment and quickly decide: boy or girl. Their own discomfort and social beliefs seemed to drive the choice, the young Vilain observed with shock. "I kept asking, 'How do you know?'" he recalls. After all, a baby's genitals might not match the reproductive organs inside.

By coincidence, Vilain was also reading the journals of Herculine Barbin, a 19th-century hermaphrodite. Her story of love and woe, edited by famed social constructionist Michel Foucault, sharpened his questions. He set on a path to find out what sexual "normality" really meant--and to find answers to the basic biology of sex differences.