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. Show notes: https://go.hubermanlab.com/iJe27oR Thank you to our sponsors AG1: https://drinkag1.com/huberman David: https://davidprotein.com/huberman Rorra: https://rorra.com/huberman Function: https://functionhealth.com/huberman Huberman Lab Instagram: https://www.instagram.com/hubermanlab Threads: https://www.threads.net/@hubermanlab X: https://x.com/hubermanlab Facebook: https://www.facebook.com/hubermanlab TikTok: https://www.tiktok.com/@hubermanlab LinkedIn: https://www.linkedin.com/in/andrew-huberman Website: https://www.hubermanlab.com Newsletter: https://www.hubermanlab.com/newsletter Dr. Marc Breedlove Website: https://marcbreedlove.com Curriculum vitae: https://docs.google.com/document/d/1mj4jJNGNUTtmiGkY9gMxRftfr4MovUD959Qi1Y-3z8Y/edit?tab=t.0 Books: https://marcbreedlove.com/books Publications: https://pubmed.ncbi.nlm.nih.gov/?term=breedlove+sm&sort=date TED talk: https://www.youtube.com/watch?v=3HX-A89XI3I Whom You Love lectures: https://www.youtube.com/user/WhomYouLove2012 YouTube: https://www.youtube.com/@Dr.Breedlove/playlists LinkedIn: https://www.linkedin.com/in/marcbreedlove Timestamps 00:00:00 Marc Breedlove 00:03:24 Hormones & Sexual Orientation 00:07:37 Prenatal Testosterone, Finger Ratio, Men & Women Differences 00:14:08 Sponsors: David & Rorra 00:16:46 Finger Ratios, Prenatal Testosterone, Gay & Straight Men/Women 00:23:57 Mice & Sex Differences, Androgens 00:26:54 Brain Differences & Sexual Orientation 00:33:52 Group vs Individual Differences, Height Analogy; Bisexuality 00:36:57 Brain Development, Hormones & Behavior; Brain Plasticity 00:42:52 Sponsor: AG1 00:44:16 Sexual Behavior, Libido 00:51:37 Gay Rams, Brain Differences 00:58:00 Aversion Pathway, Men vs Women, Same-Sex Partner 01:06:58 Congenital Adrenal Hyperplasia (CAH), Intersex Phenotypes 01:13:55 Androgen Insensitivity Syndrome (AIS) 01:18:14 Sponsor: Function 01:19:25 Gay Men & Older Brothers, Maternal Immunization Hypothesis 01:32:55 CAH Carriers, Advantage, Stress Tolerance 01:35:41 Birds & Sexual Differentiation, Gynandromorphs 01:41:32 Anabolic Steroids, Hypersexuality; Adult Brain Plasticity 01:45:31 Age & Testosterone Decline; Sexual Orientation & Activities 01:53:14 Marc’s Academic Journey, Ozarks, Luck 02:02:35 Exploration; Kids & Sex Differences 02:08:47 Zero-Cost Support, YouTube, Spotify & Apple Follow, Reviews & Feedback, Sponsors, Protocols Book, Social Media, Neural Network Newsletter #HubermanLab #Science #Hormones Disclaimer & Disclosures: https://www.hubermanlab.com/disclaimer