It's that 0.6% of DNA that makes us fully upright compared to that of a chimp, a more complex neural system, and abilities that chimps don't show development on whereas humans (such as tools) have developed. Evolutionary theory states that we all come from a common ancestor, hence the commonalities. If we really were so similar (sans the genetic similarity) then we would share more than just genetic makeup, genotypic and phenotypic expressions would be similar, but they are not.