I tend to avoid the gun debates. My dad was a big NRA fan, but no longer. For me (and it's just a personal view of no real relevance to the political struggle), I know that I very nearly managed to kill myself in my teens in part thanks to the presence of guns in the house. Fortunately, I didn't really want to do it, or I would have actually followed through. And this was in a household where gun safety was fairly and responsibly enforced... my dad was careful to make sure that we all knew how to use them properly, but also that they remained under lock and key all the time.
To me, it seems clear, and did even from NRA propaganda in the 70s, that there's a far greater risk associated with having guns in a house than the odds of preventing something bad with one or more of them, if only because good people doing stupid things at home is a lot more common than home invasions or other bad things.
At least part of the "fault" for the Connecticut shooting was the denial in the shooter's mother's mind that allowed her to decide to keep her guns in the house when she knew she had a child there who was a potential threat... but maybe she really didn't see that threat? Or did she rationalize it? I don't know... people have a tendency to not make such terrible connection, don't they?