There has never been a religious institution, parent, sibling

[malaise]

friend or any one else who could influence me into killing and maiming human beings, animals, birds or any other living creature.

Sorry - this atheist has her own moral compass and I try to practice what I preach.
I have a simple view of life - do unto others as you would have them do unto you.

How do two young men plan and plot to blow people apart? And yes I know that governments do these things to people in other countries.

If Suspect #2 is found guilty, he'll have lots of time to think about what he achieved from that horrific act.

[muriel_volestrangler]

1. Most people have a level at which some creatures become pests

Mosquitos, say. We're happy to kill them. And we pick it up from parents, siblings or friends. Most of us are happy for others to kill creatures to provide us food too, and many have done it themselves - fishing or hunting.

Are you a vegan?

[malaise]

2. Well you got me there

i eat seafood and occasionally bird.

[cali]

3. you're kind of asking the nurture/nature question, if only obliquely

perhaps the reason that you're immune to influences to harm others is as much a function of environment as anything else. I don't think I could be influenced to kill or maim people either (full confession, I have killed mice and rats and flies who invaded my living space)

When I was a little kid I used to drive people nuts by trying to rescue moths that were drowning in the swimming pool, drawn into it by the underwater lights. I think I heavily projected on the struggle of those moths, for reasons that are apparent to me now, decades later.

In the case of the Tsarnaev brothers, I suppose that they arrived at doing such violence because they believed, in some fashion, that doing so served "a higher cause". I'd further guess that the younger was influenced heavily by the older and that Tamerlan was influenced by religion, nationalism and his early experiences in childhood as well as, perhaps, something innate.

but hell, that's all just guessing.