In 2000, the BBC embarked on an ambitious experiment to follow the development of 25 UK babies over 20 years in an attempt to answer the age-old question of nature versus nurture.

Professor Robert Winston catches up with the now-16-year-olds for this two-part series and discovers, with help from Professor Tanya Byron, how our teenagers’ changing brains mean that what they do now can shape their lives for ever.

Look out for the shyest of the bunch, Matt, now being a party animal, former tomboy Megan planning a girly party and Charlie being loved-up with her first boyfriend. Concludes tomorrow.