Nettie Stevens discovered the existence of sex chromosomes. Stevens made revolutionary discoveries at a time when it was very unusual for women to be able to work in science at all. She had a goal of becoming a scientist and didn’t let anything stop her, even when that meant teaching for many years to eventually afford to attend University. Despite making groundbreaking genetic discoveries, other scientists took credit for her work and said that it was their own. Regardless, she did not allow the fact she was not recognized for her work to deter her from furthering her career.