Which logical fallacy is used in the text?
Don't try to tell me that you only watch educational programming, Kathleen! I know for a fact that your sister only watches reality television.

 - circular reasoning: an argument that supports a claim with the claim itself
 - guilt by association: a negative association intended to discredit someone or something
The text argues that Kathleen must watch reality television, because her sister watches reality television. However, even though Kathleen's sister watches reality television, that doesn't necessarily mean that Kathleen does, too. This illustrates a type of logical fallacy known as guilt by association.