A bit more astonishing DNA in numbers. About 2 grams of DNA could hold all the world's digitally stored information. Human DNA is 99.9 percent identical. The variations are the last 0.1 percent. The half-life of DNA is 521 years, and in 1.5 million years, even DNA stored at its best cannot be read. The DNA in all your cells could stretch 16 billion kilometers if spun out. That's about the distance from Earth to Pluto and back.