[smart (OP)]

Do people who commit violent crimes born this way?

What do you think?

[alancalverd]

Most active (as opposed to reactive - self-defence or revenge) violent crimes are committed by males, so there's obviously something genetic at work. Risk-taking and an enhanced physical flight-or-fight response are associated with testosterone, the level of which seems to be genetically determined.

Whether a testosterone-loaded male becomes a career criminal or a hero (Mohammed Ali, Douglas Bader.....) depends on circumstance and opportunity. Ali was lucky to meet a policeman who took him to a gym to work off his fury at having his bike stolen. Bader was lucky that a war turned up just as his boxing and cricketing career came to an end.

[Bored chemist]

Human behaviour is very complex. There are certainly genetic factors at work, but they are not the whole story.
Environmental factors matter a lot and, even with "bad" genes and a "bad" environment, we still have free will.
(or as much free will as the next person has)