I've heard that the older bro was "upset" at the Wars in Iraq and Afghanistan. Dunno why... And that may have contributed to him turning violent.
Makes sense.
Angry at pres. Bush and the American government? Go take it out on a bunch of marathon runners in Boston who had nothing to do with tnhose invasions. Kill a kid who wasn't even born when those 2 wars were started. Genius.
I stand by my original theory: the older bro was pissed for being socially awkward and for being a virgin. So he decided to take of his anger on a bunch of innocent people.
I agree with the uncle: they are losers looking for an excuse to kill.
Please don't blame the government, wars, guns, religion, or video games. Man up, and blame yourselves.