human nature 
noun [mass noun]
The general psychological characteristics, feelings, and behavioural traits of humankind, regarded as shared by all humans: he had a poor opinion of human nature...
- It's human nature for people to reveal things at one moment that they regret a week or a year later.
- It is our human nature as social animals to attempt to interact with each other in a profitable manner.
- How could you have a glowing view of human nature when you contemplate what people do to one another?