Essentially, all expressions of human nature ever produced, from a caveman's paintings to Mozart's symphonies and Einstein's view of the universe, emerge from the same source: the relentless dynamic toil of large populations of interconnected neurons.
Even two of humanity's most intimate possessions - a sense of self and a body image - are fluid, highly modifiable creations of the brain's mischievous deployment of electricity and a handful of chemicals. They both can change or be changed on less than a second's notice.