Each man inherits the same basic genetic architecture — the same fundamental catalogue of physical and psychological attributes. Each man experiences love, hatred, compassion, and sadism. Each exhibits both kindness and cruelty. The differences between men are differences of degree, not of kind.
This is not to say that all individuals are the same. Quite the contrary. The facets and nuances of human nature are myriad, and — each being expressed as a spectrum of possible values — each individual will necessarily constitute a unique expression.
It is the shared inheritance of traits, made manifest, that defines the human. It is the uniquely combined expression of these traits that defines the individual.