to wash your hand
It is a social responsibility
Everyone has their right and wrong responsibilities, that's what makes us humans.
According to the Princeton web dictionary: duty: the social force that binds you to the courses of action demanded by that force; "we must instill a sense of duty in our children"; "every ......
Responsibility lies (with Mary, for example). The word "lay" is used to indicate responsibility as well : "He wants to lay the blame on me."