I liked your post. Having worked in residential treatment for 5 years, then in a local high school for 20 years, with "at-risk" youth (I've come to believe they ALL are at risk at some time or another), your thoughts led me to recall the cognitive, emotional, and social abilities scale, wherein, if one were to have a low level of each, it would stand to reason how one reacts to stressors in their daily life often differs from one who would be possessed of a high level of same.
The curve of explosion, at it's peak, may include, among various things, a vulgar verbal request, a verbal personal attack, or an aggressive, or worse, assaultive act.
The stimulus/response cycle results in appropriate responses throughout the day, over and over, yet it only takes one time for the response to become violent.
Higher cognitive/emotional/social skill set, for the most part, minimizes the incidence of the aggressive/violent response.
Please don't hammer me for I know there are exceptions to every rule. Generally speaking here.
And so, is it not often the case, that frustration is handled differently by different persons, yes?
Speculation as it may be, I have opinions on the matter. Might something have occurred, with the adopted parents, or a loved one, or family member, who was charged with the care of these two boys, might the punishment of some behavior have been excessive? Who knows?
Mix in a little covid lockdown, home schooling requirements, possible economic challenges, and maybe even a little drug use/abuse, and where might that take the wandering mind?
I do know that many of the families that I dealt with over the years were tight. Real tight.
As I've said before, we either have a kidnapping, a murder, or a sale. Possibly a combination thereof.