: Many of us were taught biological sex is a question of female or male, XX or XY ... but it's far more complicated. On this week's show, TED speakers explore what determines our sex.

Artist Emily Quinn is intersex. She's one of over 150 million people in the world who don't fit neatly into the categories of male or female. She explains how biological sex exists on a spectrum.

Over a century ago, one part of our DNA got labelled the "sex chromosomes." Science journalist Molly Webster explains the consequences of that oversimplification.

The human body is not a patchwork of separate systems. It's intricately connected, says neuroscientist Lisa Mosconi. She explains the relationship between our brains, hormones and reproductive organs.

We're used to thinking of DNA as a rigid blueprint. Karissa Sanbonmatsu researches how our environment affects the way DNA expresses itself-especially when it comes to sex and gender.