February 18th, 2013
Episode 243 of 558 episodes
When a couple are expecting a baby, the big question is: girl or boy? Adam Rutherford explores the many ways Nature decides that question. If you're a human, a kangaroo or a komodo dragon, it's in the sex chromosomes. If you're a crocodile, it's the temperature of your eeg. And if you're a fish, it can be one sex first and, later in the life, the other.