White peacock, 1999.
© Science Museum / Science & Society Picture Library
'Your looks were determined when you were in your mother's womb. Your development as a foetus was subtly orchestrated by a set of genes that are shared by many other animals - including worms. Special genes control the distribution and survival of cells that add colour to feathers, hair and fur. A variation in these 'white spotting genes' has made this peacock lose its colour - producing cells and it's feathers that are therefore white.'