Sibling Birth Order and Its Impact on Identity and Sexuality

It’s National Siblings Day, and guest host Selena Simmons-Duffin takes a personal dive into how the number of older brothers a person has might influence their sexuality. This exploration centers on a specific concept known as the ‘fraternal birth order effect’. This effect suggests that the probability of a person being gay increases with each older brother they have.

Despite the controversial history of sexuality research, which includes harmful impacts on queer communities and debunking of early theories, the ‘fraternal birth order effect’ persists in scientific discussions. It has been observed globally, from Turkey and North America to Brazil and the Netherlands.

This episode of NPR’s Short Wave podcast delves into the details of the fraternal birth order effect, examining how it has been studied and what insights it might – or might not – offer about sexuality.

For those interested in understanding the science of familial relationships, NPR’s Science of Siblings series provides an array of stories. From exploring the origin of National Sibling Day to examining how a brother’s hormones can affect a sister’s future, the series offers engaging insights.

Listeners can engage with Short Wave across platforms such as Spotify, Apple Podcasts, and Google Podcasts. Supporting NPR’s work is possible through Short Wave+ for an ad-free experience. This episode was brought together by a team including producer Rachel Carlson, editor Rebecca Ramirez, fact-checker Brit Hanson, and audio engineer Maggie Luthar.