Understand that publishing on the genetic link to violence is a career ending event, so what literature is published is pretty oblique. but, there is no question about it. Start by Googling MAO-A and gene and you will get the drift.
Professors are fired and funding lost for any mention of this verboten topic. Like the Bell Curve was buried three decades ago.
I’m not responding to all of you on this genetic predisposition thing. Just start reading on it and you will see. It is indisputable. Just get on Google for a bit and then come back and insult me with some information where MAO A gene patterns in black populations has been refuted as a genetic marker to violence. I think you will re-assess your skepticism.