If you layout all the DNA in your body end to end, that string would be about 67 billion miles long—enough to circle the globe more than 2.5 million times. That’s your personal, very detailed book of life. Your DNA affects your eye color, the sound of your voice, your health, and on and on. The coolest thing about DNA? It makes you unique—but it also makes life on earth one big cozy family.

   What do you, your cousin, Taylor Swift, a 12th-century samurai warrior, and the person sitting next to you in class have in common? About 99.9 percent of the same DNA. Yep, just 0.1% accounts for any differences between us (3,200,000bp out of 3,2 billion bp) genetically. But our experiences and environment also shape who we are, making us a melting pot of beautiful differences.

   All life forms have a common ancestor. That’s why we’ve got thousands of genes in common with fruit, flowers, and other plants. These genetic similarities help humans and flora do essential-to-living-on-earth tasks, like process oxygen and burn glucose.

During molecular evolution certain types of viruses have hijack our bodies by inserting their own DNA into our cells, and some of them can replicate down through generations. In fact, about a whopping 8 percent of our DNA is remnants of ancient viruses that infected our primate ancestors. But a few of these viral invaders have helped humans ward off disease and even build placentas—actually keeping our species alive.