Ask the Naked Scientists, South Africa 14.04.25 - Is petrol better value when it's cold?

Summary: How can cochlear implants deliver gene therapy? Are you better off circumcised? What is the biggest discovery of the last 20 years? Can planets exist without a parent star to orbit? Does lighting a match mask a bad smell? Are there devices to help achieve perfect pitch? And do i get more petrol for my money when it is cold?