The genetic code that comprises the blueprint for life is contained in molecules of DNA, which lie folded up in the nuclei of the cells of living organisms. The width of DNA molecules is only 2 nm (but length is a different matter; human DNA, if all joined together, would come to a length of about 2 m, all of which is squeezed into a single cell nucleus). The code contained in this nano-sized molecule serves as the template for the production of amino acids, which are then combined to create the proteins that combine further to become the various parts of our bodies, or substances that perform various roles within our bodies. That is why any kind of problem cropping up in this DNA can result in life-threatening ailments. It is also tiny differences in the DNA of each and every one of us that create the characteristics that make each of us unique.

There are many kinds of other substances, too, in which just a tiny difference in the combination of their atoms can give them completely different properties.

In other words, the way the world works is decided at the nano level.