I agree that my assumption was based on hearsay. Fundamentally, I don't believe that children who are loved and protected by their primary caregivers shoot themselves in the stomach in an attempt to die.
It is possible to have a who child goes off the rails in a very nurturing and a generally normal family. I've seen cases where one of the many siblings gets to become a sociopath and the family never understands why and they continue to be normal and consistently try to get their sibling back on track. It is clear that abuse in the family doesn't always play a role. But quite often it does and while mental health has a hereditary component, a bad environment only makes things worse.
I recommend Ramsay's movie 'We need to talk about Kevin' to make an idea of how wrong it could go. Surely, it is a movie but it's not too far from reality.
I'd say that is pretty hard to tell from the hearsay and all these are just speculations, which are okay. We're learning more from these conversations anyway.