1Inside almost every cell of your body, there is a remarkable molecule that carries the instructions for building you.
2This molecule is called DNA, and it holds the complete set of instructions needed to build a living thing.
3Under a powerful microscope, DNA looks rather like a twisted ladder, with steps made of four chemical letters.
4The exact order of these letters spells out the instructions that quietly shape the story of who you are.
5By reading DNA, scientists can trace how different species are related to one another through millions of years of evolution.
6Humans, for example, share a truly surprising amount of their DNA with chimpanzees, our closest living relatives in nature.
7More astonishing still, even a humble banana shares a significant part of its genetic code with every one of us.
8Doctors can now examine a patient's DNA to discover why certain serious diseases keep running in particular families.
9In criminal investigations, police can identify a suspect from a single hair or drop of blood left at a scene.
10Researchers have even managed to recover fragments of DNA from animals that became extinct many thousands of years ago.
11Every new discovery in this field raises difficult questions about how such powerful knowledge ought to be used.
12The book of life is finally open before us, and so far we have only read its first few pages.