Boys will be boys, and girls will be girls. Or will they? A lot of people think that if you're born with a certain set of chromosomes and particular genitalia, then your gender is set for life. But things aren't that simple. They never are.

So how does sex relate to gender? Tim and Monty discuss what the latest science, anthropology and philosophy have to say about gender, and look at how sex and gender inform who we are.