Todd Sampson's Why?

The complexities of unregulated sperm donation sees half brothers and sisters all around the world. We meet a father who has children in the hundreds. Many of the mothers can't afford IVF and instead choose to go down the private path to take away some of the anonymity and costs associated with donor clinics.

At undisclosed locations around the world, 'preppers' are skilling up and hunkering down. They're getting ready for the end of days with purpose-built bunkers, stockpiled weapons, food stores and survival training. We meet a family preparing for the absolute worst.

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

How did risking your life become a hobby? Combine a healthy dose of social media, the addictive rush of adrenaline, and the rise in extreme sports, like free climbing and BASE jumping, and you might get close to an answer.