How Hormones Shape Sexual Orientation & Behavior | Dr. Marc Breedlove

Dr. Marc Breedlove, PhD, is a professor of neuroscience at Michigan State University and an expert on how hormones shape brain development and sexual orientation. We discuss how prenatal testosterone impacts whether someone is romantically attracted to men or women later in life, and what correlates of sexual orientation — such as finger-length ratios — tell us about the role of hormones in brain and psychological development. We also discuss why the number of older brothers a male has biases sexual orientation. Throughout, we explain how nature and nurture interact to shape male-female differences, behavior, and romantic partner choice.

Articles

• Finger-length ratios and sexual orientation (Nature)
• Comparison of the auditory systems of heterosexuals and homosexuals: Click-evoked otoacoustic emissions (Proceedings of the National Academy of Sciences of the United States of America)
• Spontaneous otoacoustic emissions in heterosexuals, homosexuals, and bisexuals (Journal of the Acoustical Society of America)
• A brain sexual dimorphism controlled by adult circulating androgens (Proceedings of the National Academy of Sciences of the United States of America)
• The ratio of 2nd to 4th digit length: a predictor of sperm numbers and concentrations of testosterone, luteinizing hormone and oestrogen (Human Reproduction)
• Sexual orientation is associated with 2D:4D finger length ratios in both sexes: an updated and expanded meta-analysis (Frontiers in Psychology)
• Sexual dimorphism in digit-length ratios of laboratory mice (Anatomical Record)
• A Difference in Hypothalamic Structure Between Heterosexual and Homosexual Men (Science)
• The Interstitial Nuclei of the Human Anterior Hypothalamus: An Investigation of Variation with Sex, Sexual Orientation, and HIV Status (Hormones and Behavior)
• Homosexuality in Men and Number of Older Brothers (American Journal of Psychiatry)
• Dominance, Politics, and Physiology: Voters' Testosterone Changes on the Night of the 2008 United States Presidential Election (PLOS ONE)
• Fraternal birth order and the maternal immune hypothesis of male homosexuality (Hormones and Behavior)
• Male homosexuality and maternal immune responsivity to the Y-linked protein NLGN4Y (Proceedings of the National Academy of Sciences of the United States of America)
• The Volume of a Sexually Dimorphic Nucleus in the Ovine Medial Preoptic Area/Anterior Hypothalamus Varies with Sexual Partner Preference (Endocrinology)
• Application of the quail-chick chimera system to the study of brain development and behavior (Science)
• Sex differences in response to children's toys in nonhuman primates (Cercopithecus aethiops sabaeus) (Evolution and Human Behavior)

Other Resources

• Heated Rivalry
• Marc's textbooks‍
• The Science of Sexual Orientation (CBS News)
• Bilateral gynandromorphism (The New York Times)

Huberman Lab Episodes Mentioned

• How Hormones Shape Sexual Development

People Mentioned

• Lynda Uphouse: professor of biology, Texas Woman’s University
• Cynthia Jordan: professor of neuroscience, Michigan State University
• Nicole Le Douarin: developmental biologist
• Cheryl Chase: medical activist for intersexed people
• Robert Moore: neurologist, biological rhythms
• Irving Zucker: professor of psychology, UC Berkeley