How to build a human. Part 3, The secret of sex.

The third in a four-part series of programmes looking at the origins of human life and the way in which our increasing understanding of genetics may affect this in the future. This part is about sexual reproduction. We see a man and woman enter an FMRI scanner which will produce images showing the physiology of coitus. There is an interview with a woman who is genetically a male but whose brain, after a course of testosterone, looks different when scanned. Sexual determination in the foetus is discussed with endoscopic film of foetal development. There is a discussion about genetic selection and finally, children talk about their perceptions of gender difference.