Meet the American who unlocked the science of gender, Nettie Stevens, female research pioneer

Nettie Stevens was a pioneer of genetics research, proving that sexual identity was a hereditary trait passed through chromosomes — and not determined by environment.

A pioneering cytogeneticist and researcher at Bryn Mawr College, outside Philadelphia, Stevens discovered in 1905 that sex is determined by hereditary traits passed through chromosomes.  "She was a real prodigy … She had guts!" "Stanford provided a solid foundation in biology, but Stevens was a rising talent, drawn to the cutting-edge research happening back east." "The study involved plucking the tiny gonads from mealworms, beetles and butterflies and fixing them in a solution." "Before Nobel Prize-winner Morgan had a religious conversion to chromosomes [determining sex identity], he was an opponent of the idea." "She continues to serve as an inspiration of a woman who persevered in face of the odds." Kerry J. Byrne is a lifestyle reporter with Fox News Digital.

Females are born with a pair of XX chromosomes, inheriting an X from both the mother and father. Males are born with XY chromosomes; the X is from the mother, the Y from the father.