Modern Wisdom

E1041 - #1041 - Dr Debra Lieberman - Why Don’t You Have Sex With Your Sister?

Published: January 3, 2026

Duration: 1:08:32

Dr. Debra Lieberman is an evolutionary psychologist, professor, and researcher.

Why don’t we feel sexual attraction toward our siblings or close family? Evolution seems to have hard-wired the brain to prevent inbreeding, a pattern shared with many other animals. So how does this mechanism work, and what are the moral or ethical arguments surrounding incest?

Expect to learn why evolution has designed you to not want sex with your sister, how animals actually detect who their relatives are, what the high level explanation is for why humans don’t want sex with their kin, the...