"You are not really responsible for all your own actions. We are all a product of how we where raised and the circumstances we find ourselves in."
I see where they are coming from that we are all affected by everyone else and this includes how we were parented, as well as all the other experiences we have. So yes, it is possible to say that there is much stimulus in our lives that shapes us and our actions. So when we are working on ways of holding each other accountable or ways of being with each other, we do need to figure out where to draw the line at who is responsible when something happens... unless we want a world of ambiguous responsibility, where it is not very clear to a person what actions they will be held responsible for.
So... assuming we want a world of clear and consistent responsibility:
Let's say it is proven someone murders a person, not out of self defense. Assuming we need to draw the line somewhere to hold someone responsible: Do we ask what his parents are like so that we can hold them partially responsible? Do we ask what his teachers were like and add them to our list? Do we retrace his steps for the day of the murder or the week or the year to figure out and assign varying levels of responsibility to each of those other actors in his life, including the guy who cut him off in traffic and the woman who refused to sleep with him?
OR... do we draw the line at the person who acted; the killer?
Which path is more practical? Which is more fair? Which is more sustainable? Which requires obtaining vast amounts of information and judgment of that information? Which is even possible? To say I'm not responsible for all of my own actions begs the questions, "OK... then which of your actions are you responsible for?" and "Then who is?" Do we share responsibility? How does that look? What system makes that an easy and fair thing? And what are the costs of that system?
Something else to think about: How often does choosing more responsibility mean choosing more power?