Genes are nothing more (nor less) than instructions to make proteins. This they do with a certain dull fidelity. In this sense, they are rather like the keys of a piano, each playing a single note and nothing else, which is obviously a trifle monotonous. But combine the genes, as you would combine piano keys, and you can create chords and melodies of infinite variety. Put all these genes together, and you have (to continue the metaphor) the great symphony of existence known as the human genome.
Bill Bryson in A Short History of Nearly Everything, the greatest book you’ll ever read on life, Earth, science, and the universe, although not in that order. The audiobook read by Bryson is quite a treat too; his voice is just as marvelous as his prose (even if it IS abridged from the nearly 500-page book).