National Siblings Day brings attention to various aspects of sibling relationships. One intriguing detail is how the number of older brothers may affect an individual’s sexuality. Guest host Selena Simmons-Duffin delves into this topic, examining the ‘fraternal birth order effect.’ This concept suggests an individual’s likelihood of being gay increases with each older brother.
The study of sexuality has a complicated past. Early studies caused significant harm to queer communities, and much of this research has been discredited. However, the ‘fraternal birth order effect’ remains a respected finding. It shows consistent results globally, appearing in countries like Turkey, North America, Brazil, and the Netherlands.
Simmons-Duffin explores the findings in detail, discussing what this effect reveals and its limitations in explaining sexuality. This investigation is a part of NPR’s series on the ‘Science of Siblings,’ which looks at how our closest relatives influence our lives.
Listeners can catch more episodes of the ‘Short Wave’ podcast on platforms like Spotify, Apple Podcasts, and Google Podcasts. These provide more insights sponsor-free and support NPR’s work through subscriptions like Short Wave+.
The episode was produced by Rachel Carlson, edited by Rebecca Ramirez, and fact-checked by Brit Hanson. Maggie Luthar served as the audio engineer.
More from the ‘Science of Siblings’ series: The origin story of National Sibling Day celebrates both love and grief. In the womb, a brother’s hormones might shape a sister’s future. Identical twins with autism shared similar upbringings but diverged in their life paths.
Local Coalition Fights to Keep Maine Birthing Unit Open 
Financial Assistance for Fertility Treatment: Grants, Costs, and Options 
Rising Threat of Drug-Resistant Candida Auris in the U.S. 
FDA Permits Zyn Nicotine Pouches as Lower Risk Alternative to Cigarettes 
Salad and Go Closes Locations Amid Cyclospora Outbreak Concerns 
Foodborne Pathogens Pose Growing Threats in the U.S.