Such differences may help explain accidental pregnancies among women on the pill, researchers say.

Research into the biological basis of gender identity is in its infancy, but clues are beginning to emerge.

The gel, which men rub on their upper bodies daily, delivers synthetic progestin to block the testes from producing normal levels of sperm.

Researchers solve the mystery of 15-year-old mutant ferns with disrupted sex determination.

The public may still believe that male-specific traits, such as high testosterone levels, lead to many of the gender inequalities that exist in society, but science tells a different story.

In Chapter 6, “The Hormonal Essence of the T-Rex?” author Cordelia Fine considers the biological dogma that testes, and the powerful hormones they exude, are the root of all sexual inequality.

Researchers argue for the consideration of hormones and sex chromosomes in preclinical experiments.

This year marks the 150th anniversary of an autopsy report describing the first known case of a sexual development disorder.

Stoned, Anxious, The Deeper Genome, and Testosterone

A federal advisory panel supports the US Food and Drug Administration’s approval of the first drug for female sexual dysfunction.

Sex is an inherently fascinating aspect of life. As researchers learn more and more about it, surprises regularly emerge.

Assistant professor, Psychology and Women’s Studies, University of Michigan. Age: 36

A study documents boys with autism who were exposed to elevated levels of testosterone, cortisol, and other hormones in utero.

A single molecule emitted by male goats may influence female goat physiology and behavior.

Water samples collected from natural gas extraction sites in Colorado contain hormone-disrupting chemicals linked to birth defects, infertility, and cancer.

Wired for Story, Dreamland, Homo Mysterious, and Vagina

Men and women may have different finger-length ratios as a result of different sex hormone exposure during early embryonic development.