Overview: T-Rex Blood? - Preserved soft tissue, including possible blood vessels and red blood cells, are turning up in dinosaur fossils. Epigenetics - Our lifestyles can change the way our genes are expressed, leading even identical twins to become distinct as they age. Kryptos - A coded sculpture at CIA headquarters has yet to be fully broken. Profile: Arlie Petters - A boy from a rural village in Belize grows up to become a world-class mathematician and cosmologist.