Genetic fallacy: the belief that one can explicate the meaning of a work of literature by pointing to previous works of literature (its "sources") from which it inevitably descended, as a child from a genealogical tree. This literary example of the post-hoc-ergo-propter-hoc or sequence-as-cause fallacy is also called, disparagingly, "source hunting." The genetic fallacy should not be confused with stemmatics, the bibliographic study of manuscripts by tracing changes introduced by scribes copying them from exemplars, which results in manucript families which really do look something like a genealogical "tree Like the biographical fallacy, the genetic fallacy guesses that features of the work of literature must necessarily be present because they existed in some previous source known to the author. New Criticism considers this fallacious because the current work's relationship to anything the author previously read is not a simple act of reproduction, like photocopying, but a product of complex compositional decisions involving the imagination and the decision to choose a prior work of literature to transform into the current one. Scholars of Pre-Modern literature routinely locate sources and analogues because authors of that era often learned their craft beginning as translators, and gradually developed artistic styles that resisted those of their sources. But they never believe they have explained a work's meaning completely merely by saying the author had access to some source. Moreover, claims to have discovered a source must be verified by proving the author had (or would likely have had) access to the source text. This can be very difficult to prove until the Modern Era.
Don't misunderstand the criticism of "source hunting" as a condemnation of all research into the history of a work's transmission from author to contemporary readers. In fact, profoundly important decisions about the texts you read have been made, mostly silently, by editors following a complex set of principles for determining what authors meant their texts to be. Their goal is to eliminate scribal copying errors from manuscripts and printers' typesetting errors from printed editions. For Timothy Seid's "Interpreting Ancient Manuscripts" web page summary of "textual editing" principles developed by biblical scholars, click here.