My grandparents and parents both had input (good, mediocre and sometimes bad) into my "nurturing" and therefore my mindset.Well, you are right.
The firearm had NO input into the 'raising of a criminal' since a firearm is an inanimate object but regardless the son made a choice, completely of his own volition, and without regard for how he was - or was not raised.
How often in our lifetimes have we (or maybe only some of us) knew of (or heard about) people who made bad (illegal) choices, on up to committing crimes and we either knew personally, or knew of, the parents to be fine, upstanding, law abiding citizens?
Ever been intoxicated to the point you shouldn't have been driving? I have (more than I care to admit) - and my parents certainly didn't promote me drinking and driving. Never got a DUI fortunately.
Yes, I have done stuff that they would never have done and would disapprove of, but family does impact the personality and behavior of their children - both by example and teaching of values. I have at times chosen to not follow their example (particularly in how to raise my child - and I believe she turned out better in many respects than I did because of that) and I continue to do so.