What do you mean by "spontaneous generation"? If you mean fully formed multicellular lifeforms (such as mice) appearing from nonliving matter (which used to be what people believed), yes, that's been pretty much disproven. If you mean self-replicating molecules of any kind occurring in a non-self-replicating environment, then that's so wrong it's funny, given other experiments being currently reported.
There is a theory which states that if ever anyone discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.
There is another theory which states that this has already happened.
- Douglas Adams, The Hitchhiker's Guide to the Galaxy
There are no "things that man should not know". All knowledge is potentially beneficial, but until we actually know it, we can't tell if it
is beneficial - therefore all knowledge should be actively sought.