Todd Sampson's Why?

The complexities of unregulated sperm donation sees half siblings around the world; we meet a father who has children in the hundreds; many mothers can't afford IVF and choose the private path.

Todd Sampson explores the intriguing complexities of human behaviour, driven by curiosity to understand why people act the way they do.

We meet devout members of the Aetherius Society, an international religion that believes life on Earth is guided by advanced extra-terrestrial civilisations on planets in our solar system.

How did risking your life become a hobby? Combine social media, the addictive rush of adrenaline, and the rise in extreme sports, like free climbing and BASE jumping.