A scientist at the cutting edge of germ line engineering (changing the genes of our descendants) shows how this technology is evolving so rapidly that it is becoming unstoppable - but it is also something that should be embraced rather than feared. All the research being done on changing our genes is to prevent the many genetic diseases that afflict people from Alzheimer's to common cancers. The gene technology for preventing these diseases also enables scientists to make people taller, to determine their eye colour, and soon, their intelligence. There is already a huge demand for these changes in the Far East. So genetic engineering is inevitable and coming soon. And there is nowhere to draw the boundary - should we ban it when it saves lives.when it prevents suffering? when children will be more cherished? There is no line to draw in the sand to say 'stop - no more of this amazing new medical science'. So, argues Gregory Stock, we should instead make sure that the science helps people achieve the best lives for their children - and to make the world a better place.