Sex is messy.
It’s not just about chromosomes. Or reproductive cells. Or any other binary metric. Many genetic, environmental and developmental variations can produce what are thought of as masculine and feminine traits in the same person. And so sex, scientists say, should be viewed in all its complex glory.
“Sex is a multifaceted trait that has some components that are present at birth and some components that developed during puberty, and each of these components shows variation,” says Sam Sharpe, an evolutionary biologist at Kansas State University in Manhattan.
Yet a definition of biological sex put forth by U.S. President Donald Trump designates people as either male or