I'd agree with Manapa. "Brainwashing" or "Indoctrination" is really the same thing as social conditioning and we're all mentally conditioned -- our political views, our ethical views, our opinions on social issues and religion, and so on.
Buddhism does not distinguish ethical culpability from cause & effect, unlike in western thought, where we think of cause & effect as some morally neutral happenings, like gravity, whereas ethical responsibility is something we've created and have to enforce, through laws and police. However, from a Buddhist point-of-view, the laws and police that put criminals in prison are themselves part of the cause & effect of morality, our life before this one and the life after this are also linked by the actions we take. So, it establishes the direct correlation between pain and evil, or pleasure and the good, as cause & effect, without falling into the deluded and superstitious view, of suggesting that all good and evil is punished by some kind of magic force, be it a God or the notion of karma in Hinduism or certain Mahayana sects.
When it comes to these children, it is possible that they were born into their condition of being indoctrinated into an evil ideology because the actions of the previous life landed them there. It's also possible that they were born there for no particular action of their own. Whatever the case is, within every human being is the potential to overcome their shortcomings, even if deeply ingrained by their environment. Despite the complexity of causality and any subjective feelings we might have about the matter, if a child is indoctrinated into an evil ideology and commits evil, he will generally bear the same types of consequences as an outsider who adopts the ideology of their own choosing, as a free thinking adult.