Countdown to life : the extraordinary making of you. 2/3, Against the odds.

This three-part series explores how our lives are shaped day-by-day by genetic developments in the womb. Part Two follows the middle 16 weeks of foetal development. Presenter Michael Mosley meets a woman with Immigration Delay Disease, or Adermatoglyphia. He then explains how the hormone testosterone is triggered in the womb, whilst introducing residents of a village in the Dominican Republic in which a high proportion of males are born as “Guevedoces”. Mosely explains the processes behind the development of the face. He introduces a baby with a cleft lip. Surgeon Felicity Mehendale performs surgery on the lip. Mosley discusses the propensity for humans to be right-handed. He meets Middleweight Boxer Tom Stalker, who talks about being left-handed. Mosley discusses the advantages of being left-handed for sports professionals. He moves on to explain how a foetus develops skin colour. He visits the Tanzanian football team Albino United, whose players are all albino males. Mosely explains how the human leukocyte antigen (HLA) system is developed, whilst introducing a woman suffering from Leukaemia. He explains the results of an experiment involving smell and sweat, which revealed that humans are more likely to be attracted to members of the opposite sex who have notably different immune systems to their own. A bone marrow transplant is shown, conducted at the Royal Marsden Hospital. Mosley explains the effect of testosterone on the development of brain cells in the womb, which in-turn affects behavioural traits, such as risk-taking. He talks to Surfer Laird Hamilton. Mosley explains how our brains are sexed during foetal development and visits a young transgender girl. Finally, he introduces Dr Jan Rasmussen, who helped to uncover the rare genetic condition Carnitine Transporter Disease (CTD) suffered by an abnormally large number of people on the Faroe Islands.