This paper aims to demonstrate the posthuman elements in A Number by Caryl Churchill and The Goat by Edward Albee concerning the familial relationships that emerge within these two contemporary plays. Churchill constructs the posthumanist dynamics in her work through the clone life forms that bear genetic similarities to the real children of the problematic father in the play, who is in search of total authority to abuse and violate the notion of family. While the first play emphasizes the hierarchical side of the posthuman relationships between man and clone, the second one deals with the role of animals, deconstructing the anthropocentric view. In The Goat, the unusual bond of the father with a goat is regarded as love by him, whereas it turns into some kind of a rivalry for his wife. The contrast between the father’s attitude towards his gay son and his effort to justify his sexual relationship with the animal, problematizing the borders of rape, takes the posthuman relations to an extreme level. In this context, our study shows that the line between human and inhuman is blurred, and the social and familial values become questionable in the 21st century.