I was just giving this some thought and I figured I'd toss it out there for general public consumption.
For instance, Led Zeppelin pretty much birthed arena rock. Is it their fault that within a decade corporate rock (with poster children like Styx) had arisen?
I go back and forth on it. I'd generally say no except Zep made and released "Song Remains the Same," which pretty much canonized crappy arena rock excess.
Other difficult musical parent/child relationships that spring to mind include:
In the late 1970s, Judas Priest decided to clad themselves in leather (because Rob Halford was into the gay biker look) and unleashed guitar-driven, up tempo heavy metal. Are they responsible for the hair metal that followed, most disagreeably in the form of Kip Winger?
How responsible is Husker Du for emo and the many sins created in that name? Do later purveyors like Superchunk on "Here's Where the Strings Come In" (I will be the steward of your southern lands, if you'd only take my, take my shaking hands) bear more responsibility? But even then could they have known how that would enable whiny teenagers?
Can we lump snot punk bands like Good Charlotte and Simple Plan onto the shoulders of the Circle Jerks?
Is Garth Brooks ultimately responsible for the horrors of modern country pop?
I don't pretend to have the answers to these questions. I'm curious to hear what others think and what other originals have spawned dastardly children.