description

Arguing to dismiss an idea because of where it originated - not necessarily the current arguer - is a Genetic Fallacy.

It's similar to Guilt By Association, but with the difference that GBA couples the argument to some other adherent, whereas GF couples the argument to its founder. Sort of splitting hairs, actually, because most examples of genetic argument that I've come across appear to be guilt by association anyway.

examples

"Lenin was a Jew. Modern Leninists are, therefore, part of a Jewish conspiracy, and their philosophy corrupt."