In 2000 the BBC embarked on a project to follow the lives of 25 babies from across the UK. At 16, these children of our time are almost fully grown. They are now free to live by themselves, have sex, get married, pay taxes and even have children of their own. In this episode professor Robert Winston and professor Tanya Byron discover how our teenagers' changing brains means that what they choose to do at 16, can shape their lives forever.