NONE! Unless they are truly that oblivious they had no idea their son’s mental state, that he was making IEDs in the house, they never spoke and heard any odd language...I have ZERO sympathy for the Columbine killers either. For instance, when my teenage was living in the main house, I stuck my head in his bedroom several times a week, with the auspices of checking in, looking for something, I need something in your closet, etc. AND, that was all with him being a perfect Chad, church attending, great grades, athlete, etc. These folks really had NO IDEA their son had ANY issues? I don’t buy it. They knew he was messed up and they said nothing until it was too late. I’ll speculate further, they may have been accomplices, and perceive their son to be a hero, AKA the hamas and their brave, raping, murdering or suicide vest wearing sons. I apologize in advance if that is all false.
Same page, I believe:
A parent who is so ignorant to the possibility their own child may not be normal and a danger to others - and who does cause harm - is him/herself inherently dangerous and merits:
1. Incarceration
and
2. Sterilization