In the late twentieth century, Michel Foucault expanded the concept of genealogy into a counter-history of the position of the subject which traces the development of people and societies through history. His genealogy of the subject accounts for the constitution of knowledges, discourses, domains of objects, and so forth, without having to make reference to a subject which is either transcendental in relation to the field of events or runs in its empty sameness throughout the course of history.
As Foucault discussed in his essay "Nietzsche, Genealogy, History", Foucault's ideas of genealogy were greatly influenced by the work that Nietzsche had done on the development of morals through power. Foucault also describes genealogy as a particular investigation into those elements which "we tend to feel [are] without history". This would include things such as sexuality, and other elements of everyday life. Genealogy is not the search for origins, and is not the construction of a linear development. Instead it seeks to show the plural and sometimes contradictory past that reveals traces of the influence that power has had on truth.
As one of the important theories of Michel Foucault, genealogy deconstructs truth, arguing that truth is, more often than not, discovered by chance, backed by the operation of power or the consideration of interest. Therefore, all truths are questionable. Pointing out the unreliability of truth, which is accused as "having tendency of relativity and nihilism", the theory flatly refuses the uniformity and regularity of history, emphasizing the irregularity and inconstancy of truth and toppling the notion that history progresses in a linear order.