Nearly every cell in your body has the same genetic code… So what makes brain cells different from embryonic cells, cancer, or stem cells? Recent advances demonstrate that this seemingly simple question has a sophisticated molecular answer. As a world leader in epigenetics research, Prof. Giuseppe Testa has made great strides towards understanding how cells are programmed in health and disease. His work also has dramatic implications for society: how shall we prepare for the latest developments in human biotechnology, where therapeutic and reproductive cloning are a reality?