Two good points. Adam sounds like a failed Asperger's case. Supposedly high IQ, but totally disconnected personality. In Massachusetts a few years back, there was a fatal high school stabbing by a moderate functioning Asperger's kid. He was known to be problematic, but not crazy-violent. He went off without warning, as seems to have happened here.
It's easier and better publicity to focus publicly on the gun shops than on the psychiatric profile of Mom and son. That would probably be more fruitful. I wonder if Adam was taking any meds, too. As to Adam's problems, a genetic component would not be surprising.
We know a family whose teenage son ambushed and killed both his parents with a rifle as they returned home from work one day.
This was a family active in the church, community, sports, Boy Scouts - model citizens, really. There were no warning signs that the son was troubled other than that he struggled a bit in school - maintained a C average in a very well respected school district.
The son was a minor at the time and was judged, guilty but mentally incompetent. He has been in a psychiatric facility for the past 15 years and to this day, shows no signs of remorse for what he did.
Sometimes there are no reasons and nothing to blame except the fact that there are evil and mentally/emotionally imbalanced people that just snap at some unforeseen or unanticipated point in their lives.
This is a scary thing, but it’s the fallen world we live in.