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

About this video

Huberman interviews Dr. Marc Breedlove of Michigan State University about how hormones shape sexual orientation and behavior. Dr. Breedlove describes prenatal testosterone exposure as influencing brain development, finger-length ratios and later attraction, and he explains the fraternal birth order effect: he reports that each additional older brother raises a man’s odds of being gay by about a third from a low base rate. The conversation covers circuits for attraction and aversion, rough-and-tumble and social play in children, nature-nurture interplay, and animal examples including gay rams. Dr. Breedlove and Huberman approach the topic through biology and statistics, reviewing what is known, what mechanisms are understood in animals and humans, and what remains unsettled.

Key takeaways

• Dr. Breedlove reports that more older brothers are associated with a higher probability a man will be gay, calling it a solid, repeated finding.
• Dr. Breedlove describes prenatal testosterone exposure as shaping brain development and correlating with finger-length ratios.
• Dr. Breedlove explains that attraction appears to involve both appetitive circuits and an aversive component toward the non-preferred sex.
• Huberman highlights Dr. Breedlove’s point that each pregnancy with a male leaves a biological trace affecting later male offspring.
• Dr. Breedlove discusses hormones’ influence on rough-and-tumble and social play in children.

Episode details: published March 30, 2026 · 347K views · 2:11:18 long. Summary written by Self Growth Videos from the episode itself. The science and protocols described are Andrew Huberman’s, presented for education — not medical advice. Consult a qualified professional before changing your own health practices.

← Previous: Using Salt to Optimize Mental & Physical Performance | Huberman Lab Essentials · Next: Essentials: How to Build Strength, Muscle Size & Endurance | Dr. Andy Galpin →

All Andrew Huberman videos · Andrew Huberman profile · Huberman Lab (official site)